[PATCH 0/4] "make tags" improvements

A discussion earlier today made me notice that our "make tags" target includes some cruft that we shouldn't be indexing. This fixes that, and starts indexing some of the shell scripts, which is something I've been doing in a hacky way for a while. It's very convenient when working on the test suite (especially because I can never remember which functions are declared in test-lib.sh, and which in test-lib-functions.sh).

  [1/4]: Makefile: reformat FIND_SOURCE_FILES
  [2/4]: Makefile: exclude test cruft from FIND_SOURCE_FILES
  [3/4]: Makefile: match shell scripts in FIND_SOURCE_FILES
  [4/4]: Makefile: exclude contrib from FIND_SOURCE_FILES

 Makefile | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

-Peff