make install doesn't work on MacOS

[szaffarano]

I followed the macOS instructions, but I'm not able to install gnvim:

$ brew install gtk+3 librsvg
...
$ make NOWEBKIT2GTK=1
...
$ make install
install -d "/usr/local/bin"
install -t "/usr/local/bin" ./target/release/gnvim
install: illegal option -- t
usage: install [-bCcpSsv] [-B suffix] [-f flags] [-g group] [-m mode]
               [-o owner] file1 file2
       install [-bCcpSsv] [-B suffix] [-f flags] [-g group] [-m mode]
               [-o owner] file1 ... fileN directory
       install -d [-v] [-g group] [-m mode] [-o owner] directory ...
make: *** [install] Error 64

It seems that macOS install command doesn't support the -t flag.