$ makepkg
==> Making package: pngcheck 3.0.3-2
==> Checking runtime dependencies...
==> Checking buildtime dependencies...
==> Retrieving sources...
  -> Downloading pngcheck-3.0.3.tar.gz...
  -> Found makefile.patch
==> Validating source files with sha1sums...
    pngcheck-3.0.3.tar.gz ... Passed
    makefile.patch ... Passed
==> Validating source files with sha256sums...
    pngcheck-3.0.3.tar.gz ... Passed
    makefile.patch ... Passed
==> Extracting sources...
  -> Extracting pngcheck-3.0.3.tar.gz with bsdtar
==> Starting prepare()...
patching file Makefile
Hunk #1 succeeded at 23 with fuzz 2.
==> Starting build()...
: invalid option -- '2'
: invalid option -- '4'
Usage: make [options] [target] ...
Options:
  -b, -m                      Ignored for compatibility.
  -B, --always-make           Unconditionally make all targets.
  -C DIRECTORY, --directory=DIRECTORY
                              Change to DIRECTORY before doing anything.
  -d                          Print lots of debugging information.
  --debug[=FLAGS]             Print various types of debugging information.
  -e, --environment-overrides
                              Environment variables override makefiles.
  -E STRING, --eval=STRING    Evaluate STRING as a makefile statement.
  -f FILE, --file=FILE, --makefile=FILE
                              Read FILE as a makefile.
  -h, --help                  Print this message and exit.
  -i, --ignore-errors         Ignore errors from recipes.
  -I DIRECTORY, --include-dir=DIRECTORY
                              Search DIRECTORY for included makefiles.
  -j [N], --jobs[=N]          Allow N jobs at once; infinite jobs with no arg.
  --jobserver-style=STYLE     Select the style of jobserver to use.
  -k, --keep-going            Keep going when some targets can't be made.
  -l [N], --load-average[=N], --max-load[=N]
                              Don't start multiple jobs unless load is below N.
  -L, --check-symlink-times   Use the latest mtime between symlinks and target.
  -n, --just-print, --dry-run, --recon
                              Don't actually run any recipe; just print them.
  -o FILE, --old-file=FILE, --assume-old=FILE
                              Consider FILE to be very old and don't remake it.
  -O[TYPE], --output-sync[=TYPE]
                              Synchronize output of parallel jobs by TYPE.
  -p, --print-data-base       Print make's internal database.
  -q, --question              Run no recipe; exit status says if up to date.
  -r, --no-builtin-rules      Disable the built-in implicit rules.
  -R, --no-builtin-variables  Disable the built-in variable settings.
  --shuffle[={SEED|random|reverse|none}]
                              Perform shuffle of prerequisites and goals.
  -s, --silent, --quiet       Don't echo recipes.
  --no-silent                 Echo recipes (disable --silent mode).
  -S, --no-keep-going, --stop
                              Turns off -k.
  -t, --touch                 Touch targets instead of remaking them.
  --trace                     Print tracing information.
  -v, --version               Print the version number of make and exit.
  -w, --print-directory       Print the current directory.
  --no-print-directory        Turn off -w, even if it was turned on implicitly.
  -W FILE, --what-if=FILE, --new-file=FILE, --assume-new=FILE
                              Consider FILE to be infinitely new.
  --warn-undefined-variables  Warn when an undefined variable is referenced.

This program built for x86_64-pc-linux-gnu
Report bugs to <bug-make@gnu.org>
==> ERROR: A failure occurred in build().
    Aborting...

$ cat src/pngcheck-3.0.3/Makefile
# gcc/gmake makefile for pngcheck.
# Greg Roelofs
# Last modified:  17 October 2020
#
# Invoke via:
#
#	make -f Makefile.unx
#
# This makefile assumes zlib has already been built or downloaded and is in
# a subdirectory at the same level as the current subdirectory (as indicated
# by the ZPATH macro below).  Edit as appropriate.
#
# Note that the names of the dynamic and static zlib libraries used below may
# change in later releases of the library.  This makefile builds statically
# linked executables, but that can be changed by uncommenting the appropriate
# ZLIB lines.


# macros --------------------------------------------------------------------

ZPATH = ../zlib
ZINC = -I$(ZPATH)
ZLIB = -L$(ZPATH) -lz
#ZLIB = $(ZPATH)/libz.a

INCS = 
LIBS = -lz

CC = gcc
LD = gcc
RM = rm
CFLAGS = -O -Wall $(INCS) -DUSE_ZLIB
# [note that -Wall is a gcc-specific compilation flag ("all warnings on")]
O = .o
E =

LDFLAGS =

PROG = pngcheck
PROG2 = pngsplit
PROG3 = png-fix-IDAT-windowsize

#OBJS  = $(PROG)$(O)
OBJS =

EXES = $(PROG)$(E) $(PROG2)$(E) $(PROG3)$(E)


# implicit make rules -------------------------------------------------------

.c$(O):
	$(CC) -c $(CFLAGS) $<


# dependencies --------------------------------------------------------------

all:  $(EXES)

$(PROG)$(E): $(PROG).c
	$(CC) $(CFLAGS) -o $@ $(PROG).c $(LIBS)

$(PROG2)$(E): gpl/$(PROG2).c
	$(CC) $(CFLAGS) -o $@ gpl/$(PROG2).c $(LIBS)

$(PROG3)$(E): gpl/$(PROG3).c
	$(CC) $(CFLAGS) -o $@ gpl/$(PROG3).c $(LIBS)


# maintenance ---------------------------------------------------------------

clean:
	$(RM) -f $(EXES) $(OBJS)