Work around clang-cl -FIIntrin.h workaround

Change-Id: I71e0de9e13718c1a6cd11339aba740effa2e0476

configure.ac

@@ -3684,7 +3684,19 @@ if test "$_os" = "WINNT"; then
         dnl localized
         AC_MSG_CHECKING([the dependency generation prefix (cl.exe -showIncludes)])
         echo "#include <stdlib.h>" > conftest.c
-        SHOWINCLUDES_PREFIX=`$CC $CFLAGS -c -showIncludes conftest.c 2>/dev/null | \
+        dnl Filter out -FIIntrin.h when CC points at clang-cl.exe and needs to
+        dnl explicitly state that argument:
+        my_CC=
+        for i in $CC; do
+            case $i in
+            -FIIntrin.h)
+                ;;
+            *)
+                my_CC="$my_CC $i"
+                ;;
+            esac
+        done
+        SHOWINCLUDES_PREFIX=`$my_CC $CFLAGS -c -showIncludes conftest.c 2>/dev/null | \
             grep 'stdlib\.h' | head -n1 | sed 's/ [[[:alpha:]]]:.*//'`
         rm -f conftest.c conftest.obj
         if test -z "$SHOWINCLUDES_PREFIX"; then