I was attempting to compile gnupg from git today, and encountered a frustrating
issue to get linking with libgpg-error working.

I was building on Ubuntu 14.04 and the configure script kept saying that libgpg-
error could not be found.

I installed it through apt-get and then installed it by hand and the configure
script picked up neither installation.

I then opened the configure script and saw on line 7955 and onwards:

"""
if test x"${GPG_ERROR_CONFIG}" = x ; then

if test x"${gpg_error_config_prefix}" != x ; then
   GPG_ERROR_CONFIG="${gpg_error_config_prefix}/bin/gpg-error-config"
else
  case "${SYSROOT}" in

"""

so essentially its looking for the binary in PREFIX/bin/gpg-error-config, so if
you just do ./configure then it won't pick it up as Ubuntu installs it in:

/usr/bin/gpg-error-config

and compiling from source installs in:

/usr/local/bin/gpg-error-config

I am aware that --prefix=/usr would likely fix this but it seems quite annoying to
have to track tha down versus it just working like all other packages.

Would it be possible to have the script check the environment for the executable
instead of hardcoding paths?