Make configure python version agnostic

configure.ac

@@ -25,7 +25,7 @@ m4_ifdef([AM_PROG_AR], [AM_PROG_AR])
 AC_DISABLE_STATIC
 LT_INIT([disable-static])
 AC_SYS_LARGEFILE
-AC_CHECK_PROGS([PYTHON2], [python2 python])
+AC_CHECK_PROGS([PYTHON], [python2 python python3])
 AX_CODE_COVERAGE
 
 AC_MSG_CHECKING([for native Win32])

src/gallium/auxiliary/Makefile.am

@@ -67,7 +67,7 @@ libgallium_la_SOURCES = \
 
 util/u_format_table.c: $(srcdir)/util/u_format_table.py $(srcdir)/util/u_format_pack.py $(srcdir)/util/u_format_parse.py $(srcdir)/util/u_format.csv
 	$(AM_V_at)$(MKDIR_P) util
-	$(AM_V_GEN) $(PYTHON2) $(srcdir)/util/u_format_table.py $(srcdir)/util/u_format.csv > $@
+	$(AM_V_GEN) $(PYTHON) $(srcdir)/util/u_format_table.py $(srcdir)/util/u_format.csv > $@
 
 -include $(top_srcdir)/git.mk