This patch allows "grouped targets" using the &: syntax:
tgt1 tgt2 ... tgtn &: pre1 pre2 ...
recipe
When the &: separator is used (in single or double colon forms), all
the targets are understood to be built by a single invocation of the
recipe. This is accomplished by piggy-backing on the already-existing
pattern rule feature, using the file's "also_make" list.
* NEWS: Add information about grouped targets.
* doc/make.texi (Multiple Targets): Add information on grouped targets.
(Pattern Intro): Refer to the new section to discuss multiple patterns.
* src/main.c (main): Add "grouped-targets" to .FEATURES
* src/read.c (make_word_type): Add new types for &: and &::.
(eval): Recognize the &: and &:: separator and remember when used.
(record_files): Accept an indicator of whether the rule is grouped.
If so, update also_make for each file to depend on the other files.
(get_next_mword): Recognize the &: and &:: word types.
* tests/scripts/features/grouped_targets: New test script.
* AUTHORS: Add Kaz Kylheku
