meson: enable -Wunterminated-string-initialization

With af1a6db58fde8f64edcf7d27e1f3b636c999934c, now we can build with the
option.

(cherry picked from commit f548bc4011bcdab008b125b9d0993817efa00718)
(cherry picked from commit 772549666cf291d85c28d3bfc1ab2b7227422d4f)
(cherry picked from commit da229ea)
(cherry picked from commit fbc4335)

meson.build

@@ -389,6 +389,7 @@ possible_common_cc_flags = [
         '-Wstrict-aliasing=2',
         '-Wstrict-prototypes',
         '-Wsuggest-attribute=noreturn',
+        '-Wunterminated-string-initialization',
         '-Wunused-function',
         '-Wwrite-strings',
         '-Wzero-length-bounds',