e and also sets the variable '$deplibs_check_method', and maybe
'$file_magic_cmd' when 'deplibs_check_method' is file_magic.

   'deplibs_check_method' can be one of five things:
'file_magic [REGEX]'
     looks in the library link path for libraries that have the right
     libname.  Then it runs '$file_magic_cmd' on the library and checks
     for a match against the extended regular expression REGEX.  When
     'file_magic_test_file' is set by 'libtool.m4', it is used as an
     argument to '$file_magic_cmd' to verify whether the regular
     expression matches its output, and warn the user otherwise.

'test_compile'
     just checks whether it is possible to link a program out of a list
     of libraries, and checks which of those are listed in the output of
     'ldd'.  It is currently unused, and will probably be dropped in the
     future.

'pass_all'
     will pass everything without any checking.  This may work on
     platforms where code is position-independent by default and
     inter-library dependencies are properly supported by the dynamic
     linker, for example, on DEC OSF/1 3 and 4.

'none'
     It causes deplibs to be reassigned 'deplibs=""'.  That way
     'archive_cmds' can contain deplibs on all platforms, but not have
     deplibs used unless needed.

'unknown'
     is the default for all systems unless overridden in 'libtool.m4'.
     It is the same as 'none', but it documents that we really don't
     know what the correct value should be, and we welcome patches that
     improve it.

   Then in 'ltmain.in' we have the real workhorse: a little
initialization and postprocessing (to setup/release variables for use
with eval echo libname_spec etc.)  and a case statement that decides the
method that is being used.  This is the real code... I wish I could
condense it a little more, but I don't think I can without function
calls.  I've mostly optimized it (moved things out of loops, etc.)  but
there is probably some fat left.  I thought I should stop while I was
ahead, work on whatever bugs you discover, etc. before thinking about
more than obvious optimizations.

