Add --show-full-compiler option to 'spack find'

When 'spack find' is invoked with the '--show-full-compiler' option,
the compiler flags and version are shown for each spec that is found.

share/spack/spack-completion.bash

@@ -407,9 +407,9 @@ function _spack_find {
     if $list_options
     then
         compgen -W "-h --help -s --short -p --paths -d --deps -l --long
-                    -L --very-long -f --show-flags -e --explicit
-                    -E --implicit -u --unknown -m --missing -v --variants
-                    -M --only-missing -N --namespace" -- "$cur"
+                    -L --very-long -f --show-flags --show-full-compiler
+                    -e --explicit -E --implicit -u --unknown -m --missing
+                    -v --variants -M --only-missing -N --namespace" -- "$cur"
     else
         compgen -W "$(_installed_packages)" -- "$cur"
     fi