install(1): copy metachar table from usr.bin/make

It is not worth having a dependency on usr.bin/make just for including
this small table.  The header file usr.bin/make/make.h, which is
included for consistency with the rest of the usr.bin/make code, is
using inline functions a lot and refers to several parts of make that
are completely irrelevant to usr.bin/install.

(rillig)