The build could have exhibited inconsistent behavior or simply failed if
there was another "perl" program already in path - either because it was
too old or too new, from some broken installation, or just a batch file
instead of a plain executable (which would require changing OpenSSL's
scripts to do "call perl x.pl" instead of just "perl x.pl").
This change resolves the ambiguity by putting the downloaded Perl first
in path, so that the same working version is used on all systems.
The inner CMakeLists.txt used to reference ${VERSION} everywhere except
as the working directory for patching, where ${OPENSSL_VERSION} was used
and the patches did not get applied because of that.
This changes it to use ${OPENSSL_VERSION} everywhere instead, consistent
with the name of this variable in the parent portfile.cmake.
This solves the issue where some software bundles (git) provide multiple executables in the same folder, which can override other desired programs (link.exe).
