Installation of pc files doesn't respect prefix option

[Aljosha Papsch]

Hi,

I'm installing ncurses 5.9 and have the --enable-pc-files option
enabled. When installing into a self-contained directory (with the DEST
variable to make install) for use with Stow, I noticed that the .pc
files got installed in it's own tree.

For example with --prefix=/home/al/local:

home/al/local/lib/libncursesw.so
...
usr/lib/pkgconfig/ncursesw.so

However, the last example should be
home/al/local/lib/pkgconfig/ncursesw.so.  Looking at the results, I
guess ncurses doesn't respect the --prefix option when installing the
pkg-config files.

Best regards.