meson: enable -Wunterminated-string-initialization

With af1a6db58fde8f64edcf7d27e1f3b636c999934c, now we can build with the
option.

(cherry picked from commit f548bc4011bcdab008b125b9d0993817efa00718)
(cherry picked from commit 772549666cf291d85c28d3bfc1ab2b7227422d4f)

meson.build

@@ -369,6 +369,7 @@ possible_common_cc_flags = [
         '-Wstrict-aliasing=2',
         '-Wstrict-prototypes',
         '-Wsuggest-attribute=noreturn',
+        '-Wunterminated-string-initialization',
         '-Wunused-function',
         '-Wwrite-strings',
         '-Wzero-length-bounds',