Add new patch, required ot build GDB 9.1 on latest MacOS

Author: ziopio

rtems/.gitignore

@@ -7,6 +7,7 @@ patches/*
 !patches/gcc-7.5.0-zlib-darwin-fdopen.patch
 !patches/gcc-7.5.0-darwin-arm64-host-hooks.patch
 !patches/gdb-9.1-zlib-darwin-fdopen.patch
+!patches/gdb-9.1-darwin-clang-enum-constexpr.patch
 !patches/binutils-2.34-zlib-darwin-fdopen.patch
 tar
 build

rtems/config/tools/rtems-gdb-9.1-1.cfg

@@ -13,6 +13,8 @@
 %hash sha512 gdb-9-1-linker-error-fix.diff QAtNCgJsDdfKno+IqHwqRGz1SR3YdTm34ERox2fqpgaGHI6H4GqNfmkJcJaIvSgzNxif24vqWO+bF/Djqa6wNg==
 %patch add gdb --rsb-file=gdb-9.1-zlib-darwin-fdopen.patch -p1 file://%{_topdir}/patches/gdb-9.1-zlib-darwin-fdopen.patch
 %hash sha512 gdb-9.1-zlib-darwin-fdopen.patch ecdc7ce221dd0459230dc8acb3edf08827bb61f9856360c0ab8ad85754e484d1c7aeabf34a7789b75a457bcf59ced8f8b418b0e5fb6721545c3fe3741a0addd8
+%patch add gdb --rsb-file=gdb-9.1-darwin-clang-enum-constexpr.patch -p1 file://%{_topdir}/patches/gdb-9.1-darwin-clang-enum-constexpr.patch
+%hash sha512 gdb-9.1-darwin-clang-enum-constexpr.patch gTXe5w0Q99d0+RrpRnSS1o+2CQrM4iTzdbOmX7QjkTeHZvC4TuyrW2+89a43np+CjYYOnG5caNuJfMiVLgNmFA==
 
 %if %{_build_os} == win32
   %if %{_windows_os} == cygwin

rtems/patches/gdb-9.1-darwin-clang-enum-constexpr.patch

@@ -0,0 +1,12 @@
+--- a/gdb/gdbsupport/enum-flags.h
++++ b/gdb/gdbsupport/enum-flags.h
+@@ -82,8 +82,7 @@ template<> struct integer_for_size<8, 1> { typedef int64_t type; };
+ template<typename T>
+ struct enum_underlying_type
+ {
+-  typedef typename
+-    integer_for_size<sizeof (T), static_cast<bool>(T (-1) < T (0))>::type
++  typedef typename std::underlying_type<T>::type
+     type;
+ };
+