waf: fix multiprocess compilation with msvc

scripts/build_windows_engine.sh

@@ -8,7 +8,7 @@ cd $TRAVIS_BUILD_DIR
 # NOTE: to build with other version use --msvc_version during configuration
 # NOTE: sometimes you may need to add WinSDK to %PATH%
 ./waf.bat configure -s "$TRAVIS_BUILD_DIR/SDL2_VC" -T "debug" --prefix=`pwd` || die
-./waf.bat build -j1 || die
+./waf.bat build || die
 echo After build
 
 ./waf.bat install || die

scripts/waifulib/msvcfix.py

@@ -0,0 +1,10 @@
+#!/usr/bin/env
+from waflib.TaskGen import feature, after_method
+
+@feature('c', 'cxx')
+@after_method('apply_flags_msvc')
+def make_pdb_unique(self):
+	for t in self.compiled_tasks:
+		pdb_unique_cflag = '/Fd' + t.outputs[0].change_ext('.pdb').abspath()
+		t.env.append_value('CFLAGS', pdb_unique_cflag)
+		t.env.append_value('CXXFLAGS', pdb_unique_cflag)

wscript

@@ -89,7 +89,7 @@ def configure(conf):
 	conf.env.MSVC_SUBSYSTEM = 'WINDOWS,5.01'
 	conf.env.MSVC_TARGETS = ['x86'] # explicitly request x86 target for MSVC
 	if sys.platform == 'win32':
-		conf.load('msvc msdev msvs')
+		conf.load('msvc msvcfix msdev msvs')
 	conf.load('xcompile compiler_c compiler_cxx gitversion clang_compilation_database')
 
 	# Every static library must have fPIC