Revert "Merge branch 'master' into FollowingPokemon_Gen1-3"

This reverts commit 63b2bd9a44, reversing
changes made to a716f522f3.

tools/rsfont/Makefile

@@ -1,10 +1,8 @@
 CC ?= gcc
 
 CFLAGS = -Wall -Wextra -Werror -std=c11 -O2 -DPNG_SKIP_SETJMP_CHECK
-CFLAGS += $(shell pkg-config --cflags libpng)
 
 LIBS = -lpng -lz
-LDFLAGS += $(shell pkg-config --libs-only-L libpng)
 
 SRCS = main.c convert_png.c util.c font.c