Refactoring Makefile and config.mk to make it easier to enable patches such as the ligatures patch and the sixel patch

config.mk

@@ -18,15 +18,24 @@ PKG_CONFIG = pkg-config
 # Uncomment this for the themed cursor patch / THEMED_CURSOR_PATCH
 #XCURSOR = -lXcursor
 
+# Uncomment the lines below for the ligatures patch / LIGATURES_PATCH
+#LIGATURES_C = hb.c
+#LIGATURES_H = hb.h
+#LIGATURES_INC = `$(PKG_CONFIG) --cflags harfbuzz`
+#LIGATURES_LIBS = `$(PKG_CONFIG) --libs harfbuzz`
+
+# Uncomment this for the SIXEL patch / SIXEL_PATCH
+#SIXEL_C = sixel.c sixel_hls.c
+
 # includes and libs, uncomment harfbuzz for the ligatures patch
 INCS = -I$(X11INC) \
        `$(PKG_CONFIG) --cflags fontconfig` \
        `$(PKG_CONFIG) --cflags freetype2` \
-#       `$(PKG_CONFIG) --cflags harfbuzz`
+       $(LIGATURES_INC)
 LIBS = -L$(X11LIB) -lm -lrt -lX11 -lutil -lXft ${XRENDER} ${XCURSOR}\
        `$(PKG_CONFIG) --libs fontconfig` \
        `$(PKG_CONFIG) --libs freetype2` \
-#       `$(PKG_CONFIG) --libs harfbuzz`
+       $(LIGATURES_LIBS)
 
 # flags
 STCPPFLAGS = -DVERSION=\"$(VERSION)\" -D_XOPEN_SOURCE=600