Adjust SDK and compiler settings to build on SnowLeopard / Xcode 3.2.

-- 10.3.9 SDK is gone, so use 10.4 SDK but set PowerPC to target 10.3
-- specify GCC version to be gcc 4.0
   (previously PPC was using gcc 3.3, but as of 10.3.9 that's no longer necessary)

Configurations/Snoize-Project-Global.xcconfig

@@ -1,10 +1,14 @@
 // Typically build against 10.4
 SDKROOT = /Developer/SDKs/MacOSX10.4u.sdk
+    // meaning: maximum API usage allowed is 10.4
 MACOSX_DEPLOYMENT_TARGET = 10.4
-// ... but PPC goes back to 10.3.9, using gcc 3.3
-SDKROOT_ppc = /Developer/SDKs/MacOSX10.3.9.sdk
+    // meaning: minimum machine we'll attempt to run on is 10.4
+
+// ... but on PPC we'll attempt to run on 10.3.9
 MACOSX_DEPLOYMENT_TARGET_ppc = 10.3
-GCC_VERSION_ppc = 3.3
+
+// We must use GCC 4.0 to target 10.4
+GCC_VERSION = 4.0
 
 // No need for prebinding generally; individual targets may turn it on themselves
 PREBINDING = NO