ncurses: Fix path in ncursesw.pc

ncurses: Fix path in ncursesw.pc

The file contains the the /usr/lib path from the toolchain directory and
not from the target directory. The /usr/lib directory for the toolchain
is empty and the shared library is not in the specified paths. On RISCV
the linker of util-linux was finding the libncursesw.so in my host
system, tried to link against it and failed. Fix the .pc file.

Fixes: #15942
Co-authored-by: Thomas Weißschuh <thomas@t-8ch.de>
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Link: https://github.com/openwrt/openwrt/pull/16018
Signed-off-by: Robert Marko <robimarko@gmail.com>