Use separate PDB files for compiling and linking in MSVC builds

The two PDB files that the MSVC compiler and linker create are supposed
to be handled differently and should not share the same file path.
Using the same file path for both can result in corrupted PDB files and
longer build times.

Use $${TARGET}.vc.pdb in the OBJECTS_DIR for the compiler and
$${TARGET}.pdb (the default) for the linker.

Task-number: QTBUG-53895
Change-Id: I31f06d4a674a3aa2afe5b30499bae820e5caf2c4
Reviewed-by: Oswald Buddenhagen <[email protected]>

qmake/generators/win32/msvc_nmake.cpp

@@ -409,11 +409,14 @@ void NmakeMakefileGenerator::init()
         project->values("QMAKE_DISTCLEAN").append(tgt + ".lib");
     }
     if (project->isActiveConfig("debug_info")) {
-        QString pdbfile = tgt + ".pdb";
+        // Add the compiler's PDB file.
+        QString pdbfile = var("OBJECTS_DIR") + project->first("TARGET") + ".vc.pdb";
         QString escapedPdbFile = escapeFilePath(pdbfile);
         project->values("QMAKE_CFLAGS").append("/Fd" + escapedPdbFile);
         project->values("QMAKE_CXXFLAGS").append("/Fd" + escapedPdbFile);
-        project->values("QMAKE_DISTCLEAN").append(pdbfile);
+        project->values("QMAKE_CLEAN").append(pdbfile);
+        // Add the linker's PDB file to the distclean target.
+        project->values("QMAKE_DISTCLEAN").append(tgt + ".pdb");
     }
     if (project->isActiveConfig("debug")) {
         project->values("QMAKE_CLEAN").append(tgt + ".ilk");