Add more tests from stringlib

tests/string_strcmp.c

@@ -0,0 +1,13 @@
+#include "string.h"
+
+int main(void)
+{
+  if ( strcmp(NULL, NULL) != 1 ) return 1;
+  if ( strcmp("Test", NULL) != 1 ) return 2;
+  if ( strcmp(NULL, "Test") != 1 ) return 3;
+  if ( strcmp("Test", "Test") != 0 ) return 4;
+  if ( strcmp("test", "Test") != 1 ) return 5;
+  if ( strcmp("Test1", "Test") != 1 ) return 6;
+
+  return 0;
+}

tests/string_strcmp.deps

@@ -0,0 +1 @@
+string