lib: add strcmp() implementation

Signed-off-by: Avi Kivity <avi@redhat.com>

lib/libcflat.h

@@ -42,6 +42,7 @@ extern void panic(char *fmt, ...);
 
 extern unsigned long strlen(const char *buf);
 extern char *strcat(char *dest, const char *src);
+extern int strcmp(const char *a, const char *b);
 
 extern int printf(const char *fmt, ...);
 extern int vsnprintf(char *buf, int size, const char *fmt, va_list va);

lib/string.c

@@ -20,6 +20,17 @@ char *strcat(char *dest, const char *src)
     return dest;
 }
 
+int strcmp(const char *a, const char *b)
+{
+    while (*a == *b) {
+	if (*a == '\0') {
+	    break;
+	}
+	++a, ++b;
+    }
+    return *a - *b;
+}
+
 void *memset(void *s, int c, size_t n)
 {
     size_t i;