8317601: Windows build on WSL broken after JDK-8317340

Reviewed-by: djelinski, erikj

Author: Andrew Leonard

make/autoconf/flags-cflags.m4

@@ -844,15 +844,20 @@ AC_DEFUN([FLAGS_SETUP_CFLAGS_CPU_DEP],
           ]
       )
       if test "x$FILE_MACRO_CFLAGS" != x; then
-          # Add -pathmap for all VS system include paths using Windows
-          # full Long path name that is generated by the compiler
+        # Add -pathmap for all VS system include paths using Windows
+        # full Long path name that is generated by the compiler
+        # Not enabled under WSL as there is no easy way to obtain the
+        # Windows full long paths, thus reproducible WSL builds will
+        # depend on building with the same VS toolchain install location.
+        if test "x$OPENJDK_BUILD_OS_ENV" != "xwindows.wsl1" && test "x$OPENJDK_BUILD_OS_ENV" != "xwindows.wsl2"; then
           for ipath in ${$3SYSROOT_CFLAGS}; do
               if test "x${ipath:0:2}" == "x-I"; then
                   ipath_path=${ipath#"-I"}
                   UTIL_FIXUP_WIN_LONG_PATH(ipath_path)
                   FILE_MACRO_CFLAGS="$FILE_MACRO_CFLAGS -pathmap:\"$ipath_path\"=vsi"
               fi
           done
+        fi
       fi
     fi
 

make/autoconf/util_paths.m4

@@ -120,6 +120,7 @@ AC_DEFUN([UTIL_FIXUP_PATH],
 
 ##############################################################################
 # Fixup path to be a Windows full long path
+# Note: Only supported with cygwin/msys2 (cygpath tool)
 AC_DEFUN([UTIL_FIXUP_WIN_LONG_PATH],
 [
   # Only process if variable expands to non-empty