build: Turn off tautological-constant-out-of-range-compare warning

This issues a warning when an enum value is compared to a value that is
out of range for the enum.

We do this a lot, either when using -1 for undefined values or when
comparing array sizes to enum values like so:

  enum {
    ONE,
    TWO,
    THREE
  } some_enum_value;
  const char *names= { "one", "two", "three" };

  g_assert (some_enum_value < G_N_ELEMENTS (names));

meson.build

@@ -271,6 +271,7 @@ elif cc.get_id() == 'gcc' or cc.get_id() == 'clang'
     '-Wno-c++11-extensions',
     '-Wno-missing-include-dirs',
     '-Wno-typedef-redefinition',
+    '-Wno-tautological-constant-out-of-range-compare',
     '-Wduplicated-branches',
     '-Wduplicated-cond',
     '-Wformat=2',