New comment by not-chicken on void-packages repository

https://github.com/void-linux/void-packages/pull/23337#issuecomment-663506825

Comment:
Thanks. It does have `$XBPS_CROSS_BASE`:
```
NSPR_CFLAGS='-I/usr/armv7l-linux-gnueabihf/usr/include/nspr'
JS_CONFIG_LIBS='-L/usr/armv7l-linux-gnueabihf/usr/lib -lplds4 -lplc4 -lnspr4 -L/usr/armv7l-linux-gnueabihf/usr/lib -lpthread -ldl -lm -ldl '
```
So I guess I should replace it with `/usr/` in `post_install`?