get stb_sprintf working for MD_String8s

samples/parse_check.c

@@ -19,4 +19,4 @@ int main(int argument_count, char **arguments)
     }
     
     return 0;
-}
+}

source/md_stb_sprintf.h

@@ -583,13 +583,11 @@ cl = lg;                                 \
                 MD_String8 str = va_arg(va, MD_String8);
                 
                 //- rjf: get string length
+                s = (char *)str.str;
+                sn = (const char *)(str.str + str.size);
                 l = str.size;
                 
                 //- rjf: clamp to precision
-                if (l > (stbsp__uint32)pr)
-                {
-                    l = pr;
-                }
                 lead[0] = 0;
                 tail[0] = 0;
                 pr = 0;

tests/cpp_build_test.cpp

@@ -3,8 +3,9 @@
 
 int main(void)
 {
-    MD_String8 str = "foobar"_md;
+    MD_String8 foo = "foo"_md;
+    MD_String8 bar = "bar"_md;
+    MD_String8 str = MD_PushStringF("%S%S", foo, bar);
     printf("%.*s", MD_StringExpand(str));
-    
     return 0;
 }