autoconf on windows ignores autotool macros provided by ports

[wrobelda]

Describe the bug
I am working on getting gwenhywfar port to build on Windows, which requires AUTOCONFIG option. The upstream configure.ac uses autotool macros provided by the lib's dependencies. ~~This works fine on Linux/macOS, but not on Windows. ~~ Apparently this fails on Linux, too. And it only worked on my macOS because of the libgcrypt package installed by brew.

Environment

• OS: All

To Reproduce
Steps to reproduce the behavior:

1. Checkout [libgwenhywfar] Update to 5.7.3, Fix static consumers, enable Windows #20572
2. ./vcpkg install libgwenhywfar
3. See error

Expected behavior
Autoconfig on Windows should include the macros provided by ports

Failure logs

configure.ac:681: error: possibly undefined macro: AM_PATH_LIBGCRYPT
      If this token and others are legitimate, please use m4_pattern_allow.
      See the Autoconf documentation.

[Neumann-A]

uses autotool macros provided by the lib's dependencies

a) the macros need to be installed and autoconfig needs to be setup by the port to consume it.
b) the only way vcpkg could provide a consistent m4 behavior is to supply all of the m4 scripts itself instead of using msys

So according to the file list you have/need:
libgcrypt:/share/libgcrypt/aclocal/libgcrypt.m4

the solution is in #9966 add:
set(ENV{ACLOCAL} "aclocal -I \"${CURRENT_INSTALLED_DIR}/share/libgcrypt/aclocal/\"")
to the portfile of gwenhywfar