laldetchar: capture lalsimulation dependency for packaging

(cherry picked from commit d48aa367de4f75c8477519580aa1abe8c4f52c0c)
lal.../include/lal/Makefile.am: remove ALL header links before rebuilding them

- otherwise links from e.g. from optionally-included header files can be incorrectly
  picked up by SWIG wrappings (e.g. LALXML-dependent headers in LALPulsar)
- in gnuscripts/lalsuite_swig.am: create intermediate rule between SWIG sources and
  $(swig_iface) which generates link in ../include/lal

(cherry picked from commit 46211b257f1c1ced17367450a17e853dd46fbf9b)
SWIG: check for consistent list of input header files

- swiglal_header_list.txt replaces swiglal_preproc.i as reference file
  for when SWIG interface should be regenerated; swiglal_preproc.xml
  depends on it directly, and swiglal_preproc.i -> swiglal_preproc.xml.i
- swiglal_header_list.txt is included in the distribution, and is always
  built when SWIG wrappings are enabled; its action is determined by
  $(update_swig_header_list), which updates header list if SWIG generation
  is enabled, and prints an error in SWIG generation is not enabled
- should catch any changes in interface due to different configurations,
  e.g. switching optional LALXML support in LALPulsar; will not catch changes
  to header files themselves, which is less unlikely in LALSuite packaging

(cherry picked from commit affa538faa0b8f4b09b2d8b119171323552ff80d)
Remove SWIG from build dependencies of LALSuite Debian/RPM packages

- no longer needed since SWIG sources are bundled with release tarballs

(cherry picked from commit b70c381d85766496148003df9ce263500d2c57b5)