Factorize target program transformations in the GDB_AC_TRANSFORM macro.

Factorize target program transformations in the GDB_AC_TRANSFORM macro.

This patch introduces a new M4 macro GDB_AC_TRANSFORM to avoid repeating
the common idiom which is the transformation of target program names,
i.e. from gdb to sparc64-linux-gnu-gdb.  It also makes gdb/configure.ac
and gdb/testsuite/configure.ac to use the new macro.

gdb/ChangeLog:

2015-02-18  Jose E. Marchesi  <jose.marchesi@oracle.com>

	* configure: Regenerated.
	* configure.ac: Use GDB_AC_TRANSFORM.
	* Makefile.in (aclocal_m4_deps): Added transform.m4.
	* acinclude.m4: sinclude transform.m4.
	* transform.m4: New file.
	(GDB_AC_TRANSFORM): New macro.

gdb/testsuite/ChangeLog:

2015-02-18  Jose E. Marchesi  <jose.marchesi@oracle.com>

	* configure: Regenerated.
	* configure.ac: Use GDB_AC_TRANSFORM.
	* aclocal.m4: sinclude ../transform.m4.