Restore xlocale.h compat header. (#17111)

This is a parial revert or #17022 ("Define _LIBCPP_HAS_MUSL_LIBC in
libcxx build")

Also, add a new test for this header.

Author: sbc100

system/include/compat/xlocale.h

@@ -0,0 +1,18 @@
+#ifndef _COMPAT_XLOCALE_H_
+#define _COMPAT_XLOCALE_H_
+
+#include <locale.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+long long strtoll_l(const char *start, char **end, int base, locale_t loc);
+unsigned long long strtoull_l(const char *start, char **end, int base, locale_t loc);
+long double strtold_l(const char *start, char **end, locale_t loc);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _COMPAT_XLOCALE_H_ */

system/lib/libc/compat/strtol_l.c

@@ -0,0 +1,22 @@
+#include <stdlib.h>
+#include <ctype.h>
+
+unsigned long long strtoull_l(const char *restrict s, char **restrict p, int base, locale_t loc)
+{
+	return strtoull(s, p, base);
+}
+
+long long strtoll_l(const char *restrict s, char **restrict p, int base, locale_t loc)
+{
+	return strtoll(s, p, base);
+}
+
+unsigned long strtoul_l(const char *restrict s, char **restrict p, int base, locale_t loc)
+{
+	return strtoul(s, p, base);
+}
+
+long strtol_l(const char *restrict s, char **restrict p, int base, locale_t loc)
+{
+	return strtol(s, p, base);
+}

tests/other/test_xlocale.c

@@ -0,0 +1,10 @@
+#include <xlocale.h>
+#include <stdio.h>
+
+int main() {
+  const char* input = "100001";
+  locale_t l = newlocale(LC_ALL_MASK, "C", NULL);
+  printf("strtoll_l: %lld\n", strtoll_l(input, NULL, 10, l));
+  return 0;
+}
+

tests/other/test_xlocale.out

@@ -0,0 +1 @@
+strtoll_l: 100001

tests/test_other.py

@@ -12063,3 +12063,7 @@ def test_lto_atexit(self):
     # With EXIT_RUNTIME we expect to see the dtor running.
     self.set_setting('EXIT_RUNTIME')
     self.do_runf(test_file('other/test_lto_atexit.c'), 'main done\nmy_dtor\n')
+
+  def test_xlocale(self):
+    # Test for xlocale.h compatibility header
+    self.do_other_test('test_xlocale.c')