Fix xvmc build

If we don't find xext.pc, disable xvmc instead of failing configure
Also add dependencies on xfixes and dri2proto (src/xvmc/dri2.h includes
<X11/extensions/Xfixes.h> and <X11/extensions/dri2tokens.h>).

configure.ac

@@ -152,8 +152,7 @@ if test "$VIDEO_DEBUG" = yes; then
 fi
 
 if test "$XVMC" = yes; then
-	PKG_CHECK_MODULES(XVMCLIB, [xvmc], [XVMC=yes], [XVMC=no])
-	PKG_CHECK_MODULES(XEXT, [xext])
+	PKG_CHECK_MODULES(XVMCLIB, [xvmc xext xfixes dri2proto], [XVMC=yes], [XVMC=no])
 fi
 AC_MSG_CHECKING([whether to include XvMC support])
 AC_MSG_RESULT([$XVMC])

src/xvmc/Makefile.am

@@ -31,4 +31,4 @@ libIntelXvMC_la_SOURCES = intel_xvmc.c \
 libIntelXvMC_la_CFLAGS = @XORG_CFLAGS@ @DRM_CFLAGS@ @DRI_CFLAGS@ \
 	@XVMCLIB_CFLAGS@ -I$(top_srcdir)/src -DTRUE=1 -DFALSE=0
 libIntelXvMC_la_LDFLAGS = -version-number 1:0:0
-libIntelXvMC_la_LIBADD = @DRI_LIBS@ @DRM_LIBS@ @XVMCLIB_LIBS@ @XEXT_LIBS@ -lpthread -ldrm_intel
+libIntelXvMC_la_LIBADD = @DRI_LIBS@ @DRM_LIBS@ @XVMCLIB_LIBS@ -lpthread -ldrm_intel

src/xvmc/intel_xvmc.c

@@ -25,6 +25,7 @@
  *
  */
 #include "intel_xvmc.h"
+#include "dri2.h"
 
 /* global */
 struct _intel_xvmc_driver *xvmc_driver = NULL;