MdeModulePkg RegularExpressionDxe: Update Oniguruma to 6.9.0

https://bugzilla.tianocore.org/show_bug.cgi?id=1200
Update Oniguruma to the latest version v6.9.0.
Oniguruma https://github.com/kkos/oniguruma
Verify VS2017, GCC5 build.
Verify RegularExpressionProtocol GetInfo() and Match() function.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Dongao Guo <dongao.guo@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Cinnamon Shia <cinnamon.shia@hpe.com>

MdeModulePkg/Universal/RegularExpressionDxe/Oniguruma/oniggnu.h

@@ -35,10 +35,12 @@
 extern "C" {
 #endif
 
-#define RE_MBCTYPE_ASCII         0
-#define RE_MBCTYPE_EUC           1
-#define RE_MBCTYPE_SJIS          2
-#define RE_MBCTYPE_UTF8          3
+enum {
+  RE_MBCTYPE_ASCII = 0,
+  RE_MBCTYPE_EUC   = 1,
+  RE_MBCTYPE_SJIS  = 2,
+  RE_MBCTYPE_UTF8  = 3
+};
 
 /* GNU regex options */
 #ifndef RE_NREGS