JavaScriptCore always builds without JIT on windows/msvc

When building QT on windows XP using msvc-2008, it seems that both debug and release dlls are build using ENABLE_JIT=0.

In qt\src\3rdparty\javascriptcore\JavaScriptCore\JavaScriptCore.pri :

win32-* {
CONFIG(debug):!contains(DEFINES, ENABLE_JIT=1): DEFINES+=ENABLE_JIT=0
}

I configured with configure -debug-and-release -ltcg
The resulting makefiles in qt\src\script\, Makefile.Debug and Makefile.Release both contain ENABLE_JIT=0

When I comment out the lines above, both makefiles do not contain any ENABLE_JIT and the resulting dll has JIT on

Do you have to use something like this at the top of the *.pri file?
CONFIG(debug, debug|release) {
..
} else { # Release
..
}

Addition:

I changed JavaScriptCore.pri like this:

win32-* {
CONFIG(debug, debug|release):!contains(DEFINES, ENABLE_JIT=1): DEFINES+=ENABLE_JIT=0
}

Now the generated makefiles are correct, i.e. Makefile.Debug has ENABLE_JIT=0 , MakefileRelease doesn't mention ENABLE_JIT