Use arrays rather than assigning literals to char* (warning-fix)

Integrity has a hack, to let us link to the library mmap is in, that
depends on two extern "C" symbols of type char *; but assigning a
string literal to a char * variable as initializer is a const-ness
violation (as the Integrity compiler does point out), so change the
two variables to be char[] instead of char *, so that the literals
populate (and determine the size of) the arrays, instead.

Change-Id: Iab34fb378bc0522e14539592ead066f068751ad0
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/global/qglobal.cpp

@@ -110,8 +110,8 @@ extern "C" {
     // without full system POSIX.
 #  pragma weak shm_area_password
 #  pragma weak shm_area_name
-    char *shm_area_password = "dummy";
-    char *shm_area_name = "dummy";
+    char shm_area_password[] = "dummy";
+    char shm_area_name[] = "dummy";
 }
 #endif