add check for setlocale in C library

Microsoft CRT and glibc have setlocale, but bionic doesn't

CMakeLists.txt

@@ -1039,6 +1039,17 @@ if (NOT WIN32)
 endif()
 
 if (WITH_LOCALE)
+  try_compile(HAVE_SETLOCALE ${CMAKE_BINARY_DIR}/check SOURCES ${CMAKE_SOURCE_DIR}/src/check/check_setlocale.c)
+  if (HAVE_SETLOCALE)
+    list(APPEND DEPENDENCIES_DEFINES HAVE_SETLOCALE)
+    message(STATUS "setlocale() found")
+  else()
+    if (NOT USE_MOMO)
+      message(FATAL_ERROR "setlocale() is not defined! This means the C library in your system does not support locale at all. Try enabling USE_MOMO.")
+    else()
+      message(STATUS "setlocale() is not defined")
+    endif()
+  endif()
   if (USE_MOMO)
     list(APPEND ENGINE_SOURCES src/momo/momo.c)
     list(APPEND DEPENDENCIES_DEFINES HAVE_LOCALE)

src/check/check_setlocale.c

@@ -0,0 +1,7 @@
+#include <locale.h>
+
+int main(int, char**) {
+  setlocale(LC_CTYPE,"");
+  setlocale(LC_MESSAGES,"");
+  return 0;
+}

src/main.cpp

@@ -510,6 +510,7 @@ int main(int argc, char** argv) {
 #ifdef HAVE_LOCALE
   String reqLocale=e.getConfString("locale","");
   const char* localeRet=NULL;
+#ifdef HAVE_SETLOCALE
   if ((localeRet=setlocale(LC_CTYPE,reqLocale.c_str()))==NULL) {
     logE("could not set locale (CTYPE)!");
   } else {
@@ -530,6 +531,13 @@ int main(int argc, char** argv) {
     }
 #endif
   }
+#else
+  if ((localeRet=momo_setlocale(LC_MESSAGES,reqLocale.c_str()))==NULL) {
+    logV("Momo: could not set locale!");
+  } else {
+    logV("locale: %s",localeRet);
+  }
+#endif
 
   if ((localeRet=TA_BINDTEXTDOMAIN("furnace","locale"))==NULL) {
     if ((localeRet=TA_BINDTEXTDOMAIN("furnace","../po/locale"))==NULL) {