Ignore GTK 2.0 warnings

Makefile.am

@@ -68,7 +68,7 @@ ACLOCAL_AMFLAGS = -I m4
 GIT_VERSION = `git describe --dirty --always --tags`
 GERBV_VERSION = `pkg-config --modversion libgerbv`
 
-AM_CPPFLAGS = $(BOOST_CPPFLAGS_SYSTEM) $(glibmm_CFLAGS) $(gdkmm_CFLAGS_SYSTEM) $(gerbv_CFLAGS) $(CODE_COVERAGE_CPPFLAGS) -DGIT_VERSION=\"$(GIT_VERSION)\" -Wall -Wpedantic -Wextra $(pcb2gcode_CPPFLAGS_EXTRA) $(GEOS_CFLAGS) $(GEOS_EXTRA)
+AM_CPPFLAGS = $(BOOST_CPPFLAGS_SYSTEM) $(glibmm_CFLAGS) $(gdkmm_CFLAGS_SYSTEM) $(gerbv_CFLAGS_SYSTEM) $(CODE_COVERAGE_CPPFLAGS) -DGIT_VERSION=\"$(GIT_VERSION)\" -Wall -Wpedantic -Wextra $(pcb2gcode_CPPFLAGS_EXTRA) $(GEOS_CFLAGS) $(GEOS_EXTRA)
 AM_CXXFLAGS = $(CODE_COVERAGE_CXXFLAGS) -DGIT_VERSION=\"$(GIT_VERSION)\" -DGERBV_VERSION=\"$(GERBV_VERSION)\"
 AM_LDFLAGS = $(BOOST_PROGRAM_OPTIONS_LDFLAGS)
 LIBS = $(gerbv_LIBS) $(BOOST_PROGRAM_OPTIONS_LIBS) $(CODE_COVERAGE_LIBS) $(GEOS_LIBS)

configure.ac

@@ -77,6 +77,10 @@ AC_ARG_VAR([pcb2gcode_CPPFLAGS_EXTRA], [Additional flags when compiling pcb2gcod
 CFLAGS+=" ${gerbv_CFLAGS}"
 AX_C_COMPILE_VALUE(GERBV_INTERPOLATION_LINEARx10,NEW_LINEARX10,[#include "gerbv.h"])
 
+# Ignore GTK 2.0 warnings for linux and macos.
+AC_SUBST([gerbv_CFLAGS_SYSTEM1], ['$(subst -I/usr/include/gtk-2.0,-isystem /usr/include/gtk-2.0,$(gerbv_CFLAGS))'])
+AC_SUBST([gerbv_CFLAGS_SYSTEM], ['$(subst -I/usr/local/Cellar/gtk+/2.24.32_3/include/gtk-2.0,-isystem /usr/local/Cellar/gtk+/2.24.32_3/include/gtk-2.0,$(gerbv_CFLAGS_SYSTEM1))'])
+
 # Checks for header files.
 AC_HEADER_STDC