alsa-tools: Pass ACLOCAL_FLAGS so aclocal uses the right params

alsa-tools: Pass ACLOCAL_FLAGS so aclocal uses the right params

The compile step ends regenerating the configure scripts included in
the source subdirs, for it to properly work we need to pass the
ACLOCAL_FLAGS or the .m4 files won't be found.

,----[ Build error ]
| ./ac3dec
| aclocal: warning: autoconf input should be named 'configure.ac', not 'configure.in'
| configure.in:18: warning: macro 'AM_PATH_ALSA' not found in library
| automake: warning: autoconf input should be named 'configure.ac', not 'configure.in'
| configure.in:9: warning: AM_INIT_AUTOMAKE: two- and three-arguments forms are deprecated.  For more info, see:
| configure.in:9: http://www.gnu.org/software/automake/manual/automake.html#Modernize-AM_INIT_AUTOMAKE-invocation
| automake: warning: autoconf input should be named 'configure.ac', not 'configure.in'
| test/Makefile.am:1: warning: 'INCLUDES' is the old name for 'AM_CPPFLAGS' (or '*_CPPFLAGS')
| configure.in:18: error: possibly undefined macro: AM_PATH_ALSA
|       If this token and others are legitimate, please use m4_pattern_allow.
|       See the Autoconf documentation.
| make: *** [all] Error 1
| ERROR: oe_runmake failed
`----

Reported-by: Rogerio Nunes <rogerio.nunes@freescale.com>
(From OE-Core rev: dde80e6fac83ca55644cb1b56cb55b2ba01c6564)

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>