OSX build: use autogen-template for different configure syntax

Gexiv2 and OpenSSL require an extra syntax to set prefix and libdir.
Use JHBuilds autogen-template parameter to set them properly.
OS X build: update OpenSSL dependency

Update the OpenSSL dependency to version 1.0.1g,
which fixes the SSL Heartbleed bug.
OS X build: fix poppler issues

The dependency 'Poppler' fails to build on OS X 10.9 with Clang
(Apple LLVM version 5.1 (clang-503.0.40) (based on LLVM 3.4svn))
because it contains the GCC compiler flag '-fno-check-new',
which is unsupported in Clang. Thus silencing all warnings from
this dependency.