This simple patch doubles the compile-speed of the hotspot repo on Windows

[Fredrik Öhrström]

ie. use /MP on the cl.exe command line.

On the build machine (Windows Server 2007, Visual Studio 2010, 32 HT
cores, 64GB ram) configuring with:

sh configure --enable-sjavac
--with-freetype=/cygdrive/d/tools/freetype-amd64
--with-boot-jdk=/cygdrive/d/java/jdk-7-fcs-bin-b147/

(You need to patch
src/share/classes/com/sun/tools/sjavac/server/CompilerThread.java
line 256, change equals("windows)" to startswith("windows), this fix
is going into tl soon.)

Without MP
----- Build times -------
Start 2013-02-01 12:23:50
End   2013-02-01 12:35:20
00:00:32 corba
00:04:43 hotspot
00:00:15 jaxp
00:00:24 jaxws
00:04:49 jdk
00:00:46 langtools
00:11:30 TOTAL
-------------------------

With MP
----- Build times -------
Start 2013-02-01 12:54:54
End   2013-02-01 13:03:56
00:00:31 corba
00:02:20 hotspot
00:00:14 jaxp
00:00:22 jaxws
00:04:44 jdk
00:00:46 langtools
00:09:02 TOTAL
-------------------------

For such a simple patch it is a nice speedup. Please test and see if
it improves the speed on your multi core machines.

//Fredrik

Oh, and for reference this is the speed without sjavac but with /MP.

----- Build times -------
Start 2013-02-01 13:39:38
End   2013-02-01 13:51:46
00:00:35 corba
00:02:24 hotspot
00:00:28 jaxp
00:00:36 jaxws
00:07:11 jdk
00:00:48 langtools
00:12:08 TOTAL
-------------------------

$ hg diff
diff -r 67498c863813 make/windows/makefiles/compile.make
--- a/make/windows/makefiles/compile.make       Thu Jan 17 12:16:06 2013 +0100
+++ b/make/windows/makefiles/compile.make       Fri Feb 01 13:05:08 2013 +0100
@@ -44,6 +44,7 @@
 #   /GS       Inserts security stack checks in some functions (VS2005 default)
 #   /Oi       Use intrinsics (in /O2)
 #   /Od       Disable all optimizations
+#   /MP       Use multiple cores for compilation
 #
 # NOTE: Normally following any of the above with a '-' will turn off that flag
 #
@@ -52,7 +53,7 @@
 # improving the quality of crash log stack traces involving jvm.dll.

 # These are always used in all compiles
-CXX_FLAGS=/nologo /W3 /WX
+CXX_FLAGS=/nologo /W3 /WX /MP

 # Let's add debug information when Full Debug Symbols is enabled
 !if "$(ENABLE_FULL_DEBUG_SYMBOLS)" == "1"
diff -r 67498c863813 make/windows/makefiles/sa.make
--- a/make/windows/makefiles/sa.make    Thu Jan 17 12:16:06 2013 +0100
+++ b/make/windows/makefiles/sa.make    Fri Feb 01 13:05:08 2013 +0100
@@ -108,6 +108,8 @@
 SA_LFLAGS = $(SA_LFLAGS) -map -debug
 !endif

+SA_CFLAGS = $(SA_CFLAGS) -MP
+
 # Note that we do not keep sawindbj.obj around as it would then
 # get included in the dumpbin command in build_vm_def.sh