Fastfetch: fix #517

1. Fix specifying `--set-keyless` with the same key second time won't override the value set before
2. Fix specifying `--color` second time won't clear the value set before

src/common/option.c

@@ -132,6 +132,7 @@ bool ffOptionParseBoolean(const char* str)
 
 void ffOptionParseColor(const char* value, FFstrbuf* buffer)
 {
+    ffStrbufClear(buffer);
     ffStrbufEnsureFree(buffer, 63);
 
     while(*value != '\0')