meson: Enable dev flags for cpp

Had to add a pragma around CityHash64 to make it work with
-f-visibility=hidden

Reviewed-by: Marcel Hollerbach <marcel-hollerbach@t-online.de>
Differential Revision: https://phab.enlightenment.org/D7466

meson.build

@@ -91,6 +91,7 @@ foreach cf: dev_cflags_try
   endif
 endforeach
 add_global_arguments(dev_cflags, language: 'c')
+add_global_arguments(dev_cflags, language: 'cpp')
 
 
 foreach lang : ['c', 'objc', 'cpp']

src/benchmarks/eina/city.cc

@@ -27,6 +27,8 @@
 // possible hash functions, by using SIMD instructions, or by
 // compromising on hash quality.
 
+#pragma GCC visibility push(default)
+
 #include "city.h"
 
 #include <algorithm>
@@ -305,3 +307,5 @@ uint128 CityHash128(const char *s, size_t len) {
     return CityHash128WithSeed(s, len, uint128(k0, k1));
   }
 }
+
+#pragma GCC visibility pop