Fix build on systems where "python" is python 3.

First, it changes autoconf to use a "python2" binary when available,
rather than plain "python" (which is ambiguous).  Secondly, it changes
the Makefiles to use $(PYTHON) $(PYTHON_FLAGS) rather than calling
python directly.

Signed-off-by: Xavier Chantry <chantry.xavier@gmail.com>
Signed-off-by: Matthew William Cox <matt@mattcox.ca>
Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>

configs/autoconf.in

@@ -53,7 +53,7 @@ MKDEP_OPTIONS = @MKDEP_OPTIONS@
 INSTALL = @INSTALL@
 
 # Python and flags (generally only needed by the developers)
-PYTHON2 = python
+PYTHON2 = @PYTHON2@
 PYTHON_FLAGS = -t -O -O
 
 # Library names (base name)

configure.ac

@@ -30,6 +30,7 @@ AC_PROG_CPP
 AC_PROG_CC
 AC_PROG_CXX
 AC_CHECK_PROGS([MAKE], [gmake make])
+AC_CHECK_PROGS([PYTHON2], [python2 python])
 AC_PATH_PROG([MKDEP], [makedepend])
 AC_PATH_PROG([SED], [sed])
 
@@ -1691,6 +1692,8 @@ echo ""
 echo "        CFLAGS:          $cflags"
 echo "        CXXFLAGS:        $cxxflags"
 echo "        Macros:          $defines"
+echo ""
+echo "        PYTHON2:         $PYTHON2"
 
 echo ""
 echo "        Run '${MAKE-make}' to build Mesa"

src/gallium/auxiliary/Makefile

@@ -211,16 +211,16 @@ include ../Makefile.template
 
 
 indices/u_indices_gen.c: indices/u_indices_gen.py
-	python $< > $@
+	$(PYTHON2) $< > $@
 
 indices/u_unfilled_gen.c: indices/u_unfilled_gen.py
-	python $< > $@
+	$(PYTHON2) $< > $@
 
 util/u_format_srgb.c: util/u_format_srgb.py
-	python $< > $@
+	$(PYTHON2) $< > $@
 
 util/u_format_table.c: util/u_format_table.py util/u_format_pack.py util/u_format_parse.py util/u_format.csv
-	python util/u_format_table.py util/u_format.csv > $@
+	$(PYTHON2) util/u_format_table.py util/u_format.csv > $@
 
 util/u_half.c: util/u_half.py
-	python util/u_half.py > $@
+	$(PYTHON2) util/u_half.py > $@

src/gallium/drivers/llvmpipe/Makefile

@@ -69,7 +69,7 @@ lp_test_sincos.o : sse_mathfun.h
 PROGS_DEPS := ../../auxiliary/libgallium.a
 
 lp_tile_soa.c: lp_tile_soa.py ../../auxiliary/util/u_format_parse.py ../../auxiliary/util/u_format_pack.py ../../auxiliary/util/u_format.csv
-	python lp_tile_soa.py ../../auxiliary/util/u_format.csv > $@
+	$(PYTHON2) $(PYTHON_FLAGS) lp_tile_soa.py ../../auxiliary/util/u_format.csv > $@
 
 LDFLAGS += $(LLVM_LDFLAGS)
 LIBS += -L../../auxiliary/ -lgallium libllvmpipe.a $(LLVM_LIBS) $(GL_LIB_DEPS)

src/glsl/Makefile

@@ -178,7 +178,7 @@ builtins: builtin_function.cpp builtins/profiles/* builtins/ir/* builtins/tools/
 	cp builtins/tools/builtin_function.cpp .
 	make glsl_compiler
 	@echo Regenerating builtin_function.cpp...
-	./builtins/tools/generate_builtins.py > builtin_function.cpp
+	$(PYTHON2) $(PYTHON_FLAGS) builtins/tools/generate_builtins.py > builtin_function.cpp
 	@echo Rebuilding the real compiler...
 	make glsl_compiler
 

src/mesa/drivers/dri/common/xmlpool/Makefile

@@ -62,7 +62,7 @@ clean:
 
 # Default target options.h
 options.h: t_options.h mo
-	python gen_xmlpool.py $(LANGS) > options.h
+	$(PYTHON2) $(PYTHON_FLAGS) gen_xmlpool.py $(LANGS) > options.h
 
 # Update .mo files from the corresponding .po files.
 mo: