Locale (Linux): Add LC_ALL check (#1166)

`LC_ALL`, if set, overrides every other locale-related environment
variable.

Author: TheCourierNV

src/detection/locale/locale_linux.c

@@ -4,6 +4,10 @@
 
 void ffDetectLocale(FFstrbuf* result)
 {
+    ffStrbufAppendS(result, getenv("LC_ALL"));
+    if(result->length > 0)
+        return;
+
     ffStrbufAppendS(result, getenv("LC_MESSAGES"));
     if(result->length > 0)
         return;