Review naming to follow raylib conventions

strprbrk() does not follow raylib function name convention but as it is
very similar to the standard strpbrk(), we'll keep the naming... also,
don't like to mix static functions with API functions but as strprbrk()
is just used in the two functions below, it's ok to be there... maybe it
could be refactored in a future or even move the logic inside the
required functions...

src/core.c

@@ -1346,13 +1346,12 @@ const char *GetExtension(const char *fileName)
     return (dot + 1);
 }
 
-/* "string pointer reverse break": return right-most occurrence of charset in s */
+// String pointer reverse break: returns right-most occurrence of charset in s
 static const char *strprbrk(const char *s, const char *charset)
 {
-    const char *latest_match = NULL;
-    for(; s = strpbrk(s, charset), s != NULL; latest_match=s++)
-        ;
-    return latest_match;
+    const char *latestMatch = NULL;
+    for (; s = strpbrk(s, charset), s != NULL; latestMatch = s++) { }
+    return latestMatch;
 }
 
 // Get pointer to filename for a path string