PDB error when compiling graal/substratevm/com.oracle.svm.native.libchelper

[pquiring]

When compiling graal/substractevm/com.oracle.svm.native.libchelper on Windows using latest Windows SDK I get this errors:

FAILED: cl -nologo -showIncludes -Ic:\graal\substratevm\src\com.oracle.svm.native.libchelper\include -Zi -O2 -D_LITTLE_ENDIAN -c c:\graal\substratevm\src\com.oracle.svm.native.libchelper\src\cSunMiscSignal.c -Fosrc\cSunMiscSignal.obj c:\graal\substratevm\src\com.oracle.svm.native.libchelper\src\cSunMiscSignal.c: fatal error C1041: cannot open program database 'c:\graal\substratevm\mxbuild\windows-amd64\src\com.oracle.svm.native.libchelper\vc140.pdb'; if multiple CL.EXE write to the same .PDB file, please use /FS

If I keep running mx build it will eventually work. The issue is that ninja is trying to compile the files concurrently which causes cl.exe to try and output PDB to the same file (vc140.pdb). Need to add /Fd option to cl.exe to avoid using same file.