textproc/fzf: Several fixes required after last update

1. The proper variable is MAKE_ENV, not BUILD_ENV
2. The build steps must not be surpressed! Remove "@" from build step
3. The make command is contingent on the success of the cd command, so change the concatenation (";") to AND ("&&") and run the whole thing in a subshell
4. Additional CGO_ variables are required now. Define CGO_LDFLAGS so that ncurses library can be found and add another path for CGO_CFLAGS so that ncurses_dll.h can be found.

Approved by: general and ncurses blankets