New review comment by ericonr on void-packages repository

https://github.com/void-linux/void-packages/pull/27763#discussion_r617978449

Comment:
```suggestion
make_build_args="LOCALINC=$XBPS_CROSS_BASE/usr/include
 LOCALLIB=$XBPS_CROSS_BASE/usr/lib
 FREETYPEINC=$XBPS_CROSS_BASE/usr/include/freetype2
 LDFLAGS+=\$(LIBS) CFLAGS+=\$(INCS)"
```

No need to use backslashes. And indentation should be spaces.