add all available Perl's to travis config
remove Perl 5.8 from .travis.yml because author-test-prereq
refactor lib test related link checks using ...

\%options.
re-order check_lib / check_lm

while check_lib is a very historic check, modern search_libs is the base
check_lm operates on. Re-order the functions to logically place check_lm
after search_libs to allow top-down readers remain in continuous flow :)
refactor pkg_config_package_flags for \%options

Final step in refactoring for \%options is pkg_config_package_flags.