LibC: Implement setlocale() for C locale

userspace/libraries/LibC/locale.cpp

@@ -0,0 +1,15 @@
+#include <locale.h>
+#include <string.h>
+
+// FIXME: Actually support locales
+char* setlocale(int category, const char* locale)
+{
+	(void)category;
+
+	static char s_locale[] = "C";
+	if (locale == nullptr)
+		return s_locale;
+	if (strcmp(locale, "") == 0 || strcmp(locale, "C") == 0 || strcmp(locale, "POSIX") == 0)
+		return s_locale;
+	return nullptr;
+}