string: add stubs for strcoll and strxfrm (TEST)

These extend the stub locale; strcoll is simply strcmp and strxfrm is
simply strncpy.

CMakeLists.txt

@@ -139,6 +139,7 @@ set(SOURCES
   src/libc/string/strchr.c
   src/libc/string/strchrnul.c
   src/libc/string/strcmp.c
+  src/libc/string/strcoll.c
   src/libc/string/strcpy.c
   src/libc/string/strcspn.c
   src/libc/string/strdup.c
@@ -150,7 +151,8 @@ set(SOURCES
   src/libc/string/strndup.c
   src/libc/string/strnlen.c
   src/libc/string/strrchr.c
-  src/libc/string/strspn.c)
+  src/libc/string/strspn.c
+  src/libc/string/strxfrm.c)
 
 if(vhex-generic IN_LIST TARGET_FOLDERS)
   # TODO

STATUS

@@ -117,9 +117,9 @@ DONE:       Function/symbol/macro is defined, builds, links, and is tested
      7.21.3.2  strncat: DONE
      7.21.4.1  memcmp: DONE
      7.21.4.2  strcmp: DONE
-!    7.21.4.3  strcoll: TODO
+!    7.21.4.3  strcoll: TEST
      7.21.4.4  strncmp: DONE
-!    7.21.4.5  strxfrm: TODO
+!    7.21.4.5  strxfrm: TEST
      7.21.5.1  memchr: DONE
      7.21.5.2  strchr: DONE
      7.21.5.3  strcspn: DONE

src/libc/string/strcoll.c

@@ -0,0 +1,8 @@
+#include <string.h>
+#include <locale.h>
+
+/* Stub locale: use strcmp. */
+int strcoll(char const *s1, char const *s2)
+{
+	return strcmp(s1, s2);
+}

src/libc/string/strxfrm.c

@@ -0,0 +1,8 @@
+#include <string.h>
+#include <locale.h>
+
+size_t strxfrm(char * restrict dest, char const * restrict src, size_t n)
+{
+	if(dest) strncpy(dest, src, n);
+	return strlen(src);
+}