simplify Makefile as per-target compilation flags are not needed

Per-target compilation flags (libIntelXvMC_la_CFLAGS) are required
when multiple targets which require different compiler flags,
are build in the same makefile.

Automake issues a command with -c and -o flags which not all compilers
support. The object fles are prefixed with libIntelXvMC_la.
The macro AM_PROG_CC_C_O must then be used to provide this feature
on compilers that do not have it. If not, a warning is issued at make time.

This macros checks for compiler support and if missing, uses a "compile"
script it generates in the package root directory.

Currently the driver uses per-target flags but the macro is missing.
Rather than adding the macro, this patch stops using per-target flags
by using the AM_CFLAGS variable for all targets in the makefile, as
there is only one.

Acked-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Gaetan Nadon <memsize@videotron.ca>

configure.ac

@@ -43,7 +43,6 @@ XORG_DEFAULT_OPTIONS
 # Initialize libtool
 AC_DISABLE_STATIC
 AC_PROG_LIBTOOL
-AM_PROG_CC_C_O
 
 PKG_CHECK_MODULES(GEN4ASM, [intel-gen4asm >= 1.0], [gen4asm=yes], [gen4asm=no])
 AM_CONDITIONAL(HAVE_GEN4ASM, test x$gen4asm = xyes)

src/legacy/i810/xvmc/Makefile.am

@@ -5,7 +5,7 @@ endif
 libI810XvMC_la_SOURCES = I810XvMC.c \
 			 I810XvMC.h
 
-libI810XvMC_la_CFLAGS = @CWARNFLAGS@ @XORG_CFLAGS@ @DRM_CFLAGS@ @DRI_CFLAGS@ \
-			-DTRUE=1 -DFALSE=0
+AM_CFLAGS = @CWARNFLAGS@ @XORG_CFLAGS@ @DRM_CFLAGS@ @DRI_CFLAGS@ -DTRUE=1 -DFALSE=0
+
 libI810XvMC_la_LDFLAGS = -version-number 1:0:0
 libI810XvMC_la_LIBADD = @DRI_LIBS@ @DRM_LIBS@ @XVMCLIB_LIBS@

src/xvmc/Makefile.am

@@ -16,7 +16,8 @@ libIntelXvMC_la_SOURCES = intel_xvmc.c \
         intel_batchbuffer.c            \
         intel_batchbuffer.h
 
-libIntelXvMC_la_CFLAGS = @XORG_CFLAGS@ @DRM_CFLAGS@ @DRI_CFLAGS@ \
+AM_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@ -lpthread -ldrm_intel