--- a/make/autoconf/flags-cflags.m4	Thu Mar 15 10:01:56 2018 +0100
+++ b/make/autoconf/flags-cflags.m4	Mon Jun 11 12:10:55 2018 +0200
@@ -128,16 +128,22 @@
   AC_ARG_ENABLE([warnings-as-errors], [AS_HELP_STRING([--disable-warnings-as-errors],
       [do not consider native warnings to be an error @<:@enabled@:>@])])
 
+  # Set default value.
+  if test "x$TOOLCHAIN_TYPE" = xxlc; then
+    WARNINGS_AS_ERRORS=false
+  else
+    WARNINGS_AS_ERRORS=true
+  fi
+
   AC_MSG_CHECKING([if native warnings are errors])
   if test "x$enable_warnings_as_errors" = "xyes"; then
     AC_MSG_RESULT([yes (explicitly set)])
     WARNINGS_AS_ERRORS=true
   elif test "x$enable_warnings_as_errors" = "xno"; then
-    AC_MSG_RESULT([no])
+    AC_MSG_RESULT([no (explicitly set)])
     WARNINGS_AS_ERRORS=false
   elif test "x$enable_warnings_as_errors" = "x"; then
-    AC_MSG_RESULT([yes (default)])
-    WARNINGS_AS_ERRORS=true
+    AC_MSG_RESULT([${WARNINGS_AS_ERRORS} (default)])
   else
     AC_MSG_ERROR([--enable-warnings-as-errors accepts no argument])
   fi
@@ -431,8 +437,6 @@
     CFLAGS_OS_DEF_JVM="-D_WINDOWS -DWIN32 -D_JNI_IMPLEMENTATION_"
   fi
 
-  # Setup target OS define. Use OS target name but in upper case.
-  OPENJDK_TARGET_OS_UPPERCASE=`$ECHO $OPENJDK_TARGET_OS | $TR 'abcdefghijklmnopqrstuvwxyz' 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'`
   CFLAGS_OS_DEF_JDK="$CFLAGS_OS_DEF_JDK -D$OPENJDK_TARGET_OS_UPPERCASE"
 
   #### GLOBAL DEFINES
@@ -492,6 +496,7 @@
   elif test "x$TOOLCHAIN_TYPE" = xmicrosoft; then
     ALWAYS_DEFINES_JDK="-DWIN32_LEAN_AND_MEAN -D_CRT_SECURE_NO_DEPRECATE \
         -D_CRT_NONSTDC_NO_DEPRECATE -DWIN32 -DIAL"
+    ALWAYS_DEFINES_JVM="-DNOMINMAX -DWIN32_LEAN_AND_MEAN"
   fi
 
   ###############################################################################