scons: A few fixes for building mesa on windows.
diff --git a/src/mesa/SConscript b/src/mesa/SConscript
index 80fbdb4..6b99dac 100644
--- a/src/mesa/SConscript
+++ b/src/mesa/SConscript
@@ -12,9 +12,19 @@
 	'#/src/mesa/main',
 ])
 
-env.Append(CFLAGS = [
-	'-std=c99',
-])
+if gcc:
+	env.Append(CFLAGS = [
+		'-std=c99',
+	])
+
+# x86 assembly
+if x86 and gcc:
+	env.Append(CPPDEFINES = [
+		'USE_X86_ASM', 
+		'USE_MMX_ASM',
+		'USE_3DNOW_ASM',
+		'USE_SSE_ASM',
+	])
 
 
 #######################################################################
@@ -269,7 +279,7 @@
 	'sparc/glapi_sparc.S',
 ]
 
-if x86:
+if x86 and gcc:
 	ASM_SOURCES = ASM_C_SOURCES + X86_SOURCES 
 	API_SOURCES = X86_API
 else: