Misc updates to header-symbol-search and handy_funcs

Misc updates to header-symbol-search and handy_funcs

header-symbol-search had broken, grep's '--mmap' option no longer
exists.  This patch fixes that, as well as getting rid of an obnoxious
loop.

In handy_funcs, the vtar and xtar functions have been replaced with
far simpler shell aliases.  See:

  vtar is aliased to 'less'
  xtar is aliased to 'tar xf'

	* usr/bin/header-symbol-search (all_headers): Removed.
	Forget slow-as-fuck looping, just recurse.

	* etc/pkgusr/handy_funcs (xtar,vtar): Replaced with simpler
	aliases.

Signed-off-by: Steve Youngs <steve@steveyoungs.com>