bare-arm/lib: Add minimal strncmp implementation.

Required by upcoming qstr sorting.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>

ports/bare-arm/lib.c

@@ -109,16 +109,23 @@ char *strchr(const char *s, int c) {
     return NULL;
 }
 
-int strcmp(const char *s1, const char *s2) {
-    while (*s1 && *s2) {
+int strncmp(const char *s1, const char *s2, size_t n) {
+    while (*s1 && *s2 && n-- > 0) {
         int c = *s1++ - *s2++;
         if (c) {
             return c;
         }
     }
+    if (n == 0) {
+        return 0;
+    }
     return *s1 - *s2;
 }
 
+int strcmp(const char *s1, const char *s2) {
+    return strncmp(s1, s2, 0x7fffffff);
+}
+
 size_t strlen(const char *s) {
     const char *ss = s;
     while (*ss) {