gdb: fix clang build failure in msymbol_is_mips

Building with clang++-14, I see:

      CXX    mips-tdep.o
    /home/smarchi/src/binutils-gdb/gdb/mips-tdep.c:453:12: error: use of bitwise '|' with boolean operands [-Werror,-Wbitwise-instead-of-logical]
      return !(MSYMBOL_TARGET_FLAG_MIPS16 (msym)
              ~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    /home/smarchi/src/binutils-gdb/gdb/mips-tdep.h:54:2: note: expanded from macro 'MSYMBOL_TARGET_FLAG_MIPS16'
            (sym)->target_flag_1 ()
            ^
    /home/smarchi/src/binutils-gdb/gdb/mips-tdep.c:453:12: note: cast one or both operands to int to silence this warning
    /home/smarchi/src/binutils-gdb/gdb/mips-tdep.h:54:2: note: expanded from macro 'MSYMBOL_TARGET_FLAG_MIPS16'
            (sym)->target_flag_1 ()
            ^

That's since commit e165fcef1e7 ("gdb: remove MSYMBOL_TARGET_FLAG_{1,2}
macros").  Fix this by using the boolean || rather than the bitwise |,
since the new methods return bool values.  No change in behavior
expected.

Change-Id: Ia82664135aa25db64c29c92f5c1141859d345bf7