bug#15664: grep snapshot compatibility issues with Automake 1.14?

[Paul Eggert]

I'm getting the following diagnostics after I touch configure.ac
and then run 'make'.  I'm using Fedora 19 but with automake 1.14
installed by hand.  Are these diagnostics intended?  I.e., should
we worry about them now or wait until after the next grep release?
They don't seem urgent but they are mildly annoying.

make 
CDPATH="${ZSH_VERSION+.}:" && cd . && /bin/sh 
/home/eggert/src/gnu/grep/build-aux/missing aclocal-1.14 -I m4
 cd . && /bin/sh /home/eggert/src/gnu/grep/build-aux/missing automake-1.14 --gnu
lib/gnulib.mk:31: warning: source file 'glthread/lock.c' is in a subdirectory,
lib/gnulib.mk:31: but option 'subdir-objects' is disabled
lib/Makefile.am:28:   'lib/gnulib.mk' included from here
automake-1.14: warning: possible forward-incompatibility.
automake-1.14: At least a source file is in a subdirectory, but the 
'subdir-objects'
automake-1.14: automake option hasn't been enabled.  For now, the corresponding 
output
automake-1.14: object file(s) will be placed in the top-level directory.  
However,
automake-1.14: this behaviour will change in future Automake versions: they will
automake-1.14: unconditionally cause object files to be placed in the same 
subdirectory
automake-1.14: of the corresponding sources.
automake-1.14: You are advised to start using 'subdir-objects' option 
throughout your
automake-1.14: project, to avoid future incompatibilities.
lib/gnulib.mk:31: warning: source file 'glthread/threadlib.c' is in a 
subdirectory,
lib/gnulib.mk:31: but option 'subdir-objects' is disabled
lib/Makefile.am:28:   'lib/gnulib.mk' included from here
lib/gnulib.mk:2797: warning: source file 'unistr/u8-mbtoucr.c' is in a 
subdirectory,
lib/gnulib.mk:2797: but option 'subdir-objects' is disabled
lib/Makefile.am:28:   'lib/gnulib.mk' included from here
lib/gnulib.mk:2805: warning: source file 'unistr/u8-uctomb.c' is in a 
subdirectory,
lib/gnulib.mk:2805: but option 'subdir-objects' is disabled
lib/Makefile.am:28:   'lib/gnulib.mk' included from here
lib/gnulib.mk:2805: warning: source file 'unistr/u8-uctomb-aux.c' is in a 
subdirectory,
lib/gnulib.mk:2805: but option 'subdir-objects' is disabled
lib/Makefile.am:28:   'lib/gnulib.mk' included from here
lib/gnulib.mk:2845: warning: source file 'uniwidth/width.c' is in a 
subdirectory,
lib/gnulib.mk:2845: but option 'subdir-objects' is disabled
lib/Makefile.am:28:   'lib/gnulib.mk' included from here