Huge cleanup. Group into sections: hardware feature detection, extension

detection/configuration, DDX options. Make building of Xorg DDX fully
    optional. Clarify and correct some help texts. Change all comments to
    use dnl instead of #. Quote all tests correctly, and guard
    pure-variable tests with 'x' (e.g. test $DMX = yes -> test "x$DMX" =
    xyes). Since the DDXes seem to have pretty divergent extension support
    these days, get rid of EXTENSION_LIBS, DMX_EXTENSIONS and
    XPRINT_EXTENSIONS, and go back to building extension lists by hand in
    the DDX-specific sections. Use portable POSIX constructs everywhere
    (e.g. test foo && test bar, instead of test foo -a bar).
Clean up old cruft.
Set _XSERVER64 on 64-bit architectures, and use x86_64 for host_cpu instead
    of amd64 (Jürg Billeter).

hw/xfree86/common/Makefile.am

@@ -1,45 +1,27 @@
 noinst_LIBRARIES = libcommon.a libinit.a
 
-if XORG_BUS_SBUS
+if XORG_BUS_SPARC
 SBUS_SOURCES = xf86sbusBus.c
 endif
 
-#if DEBUG
-#DEBUGSOURCES = xf86Debug.c
-#endif
+if DEBUG
+DEBUGSOURCES = xf86Debug.c
+endif
 
-#if BUILDXV
+if XV
 XVSOURCES = xf86xv.c xf86xvmc.c
 XVSDKINCS = xf86xv.h xf86xvmc.h
-#endif
+endif
 
-#if XKB
 XKBSOURCES = xf86XKB.c
-#endif
-
-#if XINPUT
 XISOURCES = xf86Xinput.c xisb.c
 XISDKINCS = xf86Xinput.h xisb.h
-#endif
-
 RANDRSOURCES = xf86RandR.c
 
 BUSSOURCES = xf86isaBus.c xf86pciBus.c xf86fbBus.c xf86noBus.c $(SBUS_SOURCES)
 
-#if LINUX
-#KBDSOURCES = xf86KbdLnx.c
-# XXX psuedocodeish
-#else if BSD
-#KBDSOURCES = xf86KbdBSD.c
-#else if Mach && !GNU/Mach
-#KBDSOURCES = xf86KbdMach.c
-#else
-#KBDSOURCES = xf86Kbd.c
-#endif
 KBDSOURCES = xf86Kbd@XORG_OS_KBD@.c
 
-# shouldn't isaBus and pciBus only be built on the relevant architectures? -ds
-# ditto DoScanPci
 AM_LDFLAGS = -r
 libcommon_a_SOURCES = xf86Configure.c xf86Bus.c xf86Config.c \
                       xf86Cursor.c xf86DGA.c xf86DPMS.c xf86DefModes.c \