Fixing bug 403758. Builds with MozillaBuild's start-msvc9.bat use the wrong SDK. r=ted.mielczarek@gmail.com

tools/build-environment/win32/guess-msvc.bat

@@ -73,6 +73,13 @@ SET SDK2003SP1KEY=%SDKROOTKEY%\8F9E5EF3-A9A5-491B-A889-C58EFFECE8B3
 SET SDK2003SP2KEY=%SDKROOTKEY%\D2FF9F89-8AA2-4373-8A31-C838BF4DBBE1
 SET SDK6KEY=HKLM\SOFTWARE\Microsoft\Microsoft SDKs\Windows\v6.0\WinSDKBuild
 
+REG QUERY "%SDK6KEY%" /v InstallationFolder >nul 2>nul
+if "%SDKDIR%"=="" (
+  IF %ERRORLEVEL% EQU 0 (
+    FOR /F "tokens=2* usebackq delims=	 " %%A IN (`REG QUERY "HKLM\SOFTWARE\Microsoft\Microsoft SDKs\Windows\v6.0\WinSDKBuild" /v InstallationFolder`) DO SET SDKDIR=%%B
+  )
+)
+
 REG QUERY "%SDK2003SP2KEY%" /v "Install Dir" >nul 2>nul
 if "%SDKDIR%"=="" (
   IF %ERRORLEVEL% EQU 0 (
@@ -87,13 +94,6 @@ if "%SDKDIR%"=="" (
   )
 )
 
-REG QUERY "%SDK6KEY%" /v InstallationFolder >nul 2>nul
-if "%SDKDIR%"=="" (
-  IF %ERRORLEVEL% EQU 0 (
-    FOR /F "tokens=2* usebackq delims= " %%A IN (`REG QUERY "HKLM\SOFTWARE\Microsoft\Microsoft SDKs\Windows\v6.0\WinSDKBuild" /v InstallationFolder`) DO SET SDKDIR=%%B
-  )
-)
-
 ECHO Visual C++ 6 directory: %VC6DIR%
 ECHO Visual C++ 7.1 directory: %VC71DIR%
 ECHO Visual C++ 8 directory: %VC8DIR%