Subject: Fix build system

- unbundle libjpeg
- unbundle libpng
- unbundle zlib
- remove dependency on libXp
- don't override CFLAGS
- remove MOTIFI/MOTIFL and /opt/X11 from flags

diff --git a/GUI/xephem/Makefile b/GUI/xephem/Makefile
index 07bb55e348a7..0c62de0bec28 100644
--- a/GUI/xephem/Makefile
+++ b/GUI/xephem/Makefile
@@ -10,9 +10,9 @@
 # one executable, xephem.
 
 # These -I and -L flags point to the supporting XEphem libraries
-LIBINC = -I../../libastro -I../../libip -I../../liblilxml -I../../libjpegd -I../../libpng -I../../libz
-LIBLNK = -L../../libastro -L../../libip -L../../liblilxml -L../../libjpegd -L../../libpng -L../../libz
-LIBLIB = -lastro -lip -llilxml -ljpegd -lpng -lz
+LIBINC = -I../../libastro -I../../libip -I../../liblilxml
+LIBLNK = -L../../libastro -L../../libip -L../../liblilxml
+LIBLIB = -lastro -lip -llilxml -ljpeg -lpng -lz
 
 # MOTIFI is the directory containing the Xm directory of include files.
 # MOTIFL is the directory containing the libXm.a library.
@@ -32,8 +32,8 @@ endif
 # for linux and Apple OS X
 CC = gcc
 CLDFLAGS = -g
-CFLAGS = $(LIBINC) $(CLDFLAGS) -O2 -Wall -I$(MOTIFI) -I/opt/X11/include
-LDFLAGS = $(LIBLNK) $(CLDFLAGS) -L$(MOTIFL) -L/opt/X11/lib
+CFLAGS += $(LIBINC) $(CLDFLAGS) -Wall
+LDFLAGS = $(LIBLNK) $(CLDFLAGS)
-XLIBS = -lXm -lXp -lXt -lXext -lXmu -lX11
+XLIBS = -lXm -lXt -lXext -lXmu -lX11
 LIBS = $(XLIBS) $(LIBLIB) -lm
 
@@ -195,12 +195,9 @@ xephem.1: xephem.man
 	nroff -man $? > $@
 
 libs:
-	cd ../../libastro; make
-	cd ../../libip; make
-	cd ../../libjpegd; make
-	cd ../../liblilxml; make
-	cd ../../libpng; make
-	cd ../../libz; make
+	${MAKE} -C ../../libastro
+	${MAKE} -C ../../libip
+	${MAKE} -C ../../liblilxml
 
 clean:
 	rm -fr *.o ../../lib*/*.[ao]