Unix|Fixed: Set en_US locale for libc and Qt

Doomsday expects U.S. English number and time formatting, so force the
en_US locale for both libc and Qt.

doomsday/engine/portable/src/dd_init.cpp

@@ -131,7 +131,7 @@ int main(int argc, char** argv)
     de::App dengApp(argc, argv, useGUI);
 
     // Override the system locale (affects number/time formatting).
-    QLocale::setDefault(QLocale::c());
+    QLocale::setDefault(QLocale("en_US.UTF-8"));
 
     // Metadata.
     QApplication::setOrganizationDomain("dengine.net");

doomsday/engine/unix/src/dd_uinit.c

@@ -35,6 +35,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <limits.h>
+#include <locale.h>
 #include <SDL.h>
 
 #include <de/c_wrapper.h>
@@ -361,6 +362,9 @@ boolean DD_Unix_Init(int argc, char** argv)
 
     memset(&app, 0, sizeof(app));
 
+    // We wish to use U.S. English formatting for time and numbers.
+    setlocale(LC_ALL, "en_US.UTF-8");
+
 #if 0
     // SDL lock key behavior: send up event when key released.
     setenv("SDL_DISABLE_LOCK_KEYS", "1", true);