w3m: Depends on homebrew/dupes/ncurses for Linuxbrew
w3m: Depends on homebrew/dupes/ncurses for Linuxbrew

Fix error:
terms.c:(.text+0x2bf): undefined reference to `tgetnum'

Closes Linuxbrew/homebrew-core#924.

Signed-off-by: Bob W. Hogg <c772a964fd55352a3510e5d535dd9ccc9ac30168@linux.com>

maxim-belkin/homebrew-core,maxim-belkin/homebrew-core,rwhogg/homebrew-core,LinuxbrewTestBot/homebrew-core,Linuxbrew/homebrew-core,Linuxbrew/homebrew-core,LinuxbrewTestBot/homebrew-core,rwhogg/homebrew-core