gdb: fix clang integer value -1 outside valid range error

Backport gdb patch to fix the "integer value -1 is outside the valid range of values" errors when building with clang 16+.

Without the patch, when using clang 16 to build, we get some errors like:
    In file included from cp-valprint.c:20:
    In file included from ./defs.h:65:
    ./../gdbsupport/enum-flags.h:85:52: error: integer value -1 is outside the valid range of values [0, 15] for the enumeration type 'ui_out_flag' [-Wenum-constexpr-conversion]
       85 |     integer_for_size<sizeof (T), static_cast<bool>(T (-1) < T (0))>::type
          |                                                    ^                                           ^

GDB ignore -Wenum-constexpr-conversion around enum-flags.h to solve the problem.

Related GDB commit：
8cbde735e405 "gdbsupport: ignore -Wenum-constexpr-conversion in enum-flags.h"

gdb-10.2.patch

@@ -16118,3 +16118,46 @@ exit 0
        subclass (SYMBOL_NONE)
      {
        /* We can't use an initializer list for members of a base class, and
+--- gdb-10.2/gdbsupport/enum-flags.h.orig
++++ gdb-10.2/gdbsupport/enum-flags.h
+@@ -81,9 +81,12 @@
+ template<typename T>
+ struct enum_underlying_type
+ {
++  DIAGNOSTIC_PUSH
++  DIAGNOSTIC_IGNORE_ENUM_CONSTEXPR_CONVERSION
+   typedef typename
+     integer_for_size<sizeof (T), static_cast<bool>(T (-1) < T (0))>::type
+     type;
++  DIAGNOSTIC_POP
+ };
+
+ template <typename E>
+
+--- gdb-10.2/include/diagnostics.h.orig
++++ gdb-10.2/include/diagnostics.h
+@@ -61,6 +61,24 @@
+ # define DIAGNOSTIC_IGNORE_FORMAT_NONLITERAL \
+   DIAGNOSTIC_IGNORE ("-Wformat-nonliteral")
+
++# if __has_warning ("-Wuser-defined-warnings")
++#  define DIAGNOSTIC_IGNORE_USER_DEFINED_WARNINGS \
++   DIAGNOSTIC_IGNORE ("-Wuser-defined-warnings")
++# endif
++
++# if __has_warning ("-Wunused-but-set-variable")
++#  define DIAGNOSTIC_IGNORE_UNUSED_BUT_SET_VARIABLE \
++   DIAGNOSTIC_IGNORE ("-Wunused-but-set-variable")
++# endif
++
++# define DIAGNOSTIC_ERROR_SWITCH \
++  DIAGNOSTIC_ERROR ("-Wswitch")
++
++# if __has_warning ("-Wenum-constexpr-conversion")
++#  define DIAGNOSTIC_IGNORE_ENUM_CONSTEXPR_CONVERSION \
++   DIAGNOSTIC_IGNORE ("-Wenum-constexpr-conversion")
++# endif
++
+ #elif defined (__GNUC__) /* GCC */
+
+ # if __GNUC__ >= 7