Honor an existing CC_FOR_BUILD in the environment for sim.

Honor an existing CC_FOR_BUILD in the environment for sim.

This matches the equivalent bits in bfd/acinclude.m4

sim/ChangeLog:

	* configure.ac: Honor existing CC_FOR_BUILD in environment.
	* configure: Regenerate.

sim/aarch64/ChangeLog:

	* configure: Regenerate.

sim/arm/ChangeLog:

	* configure: Regenerate.

sim/avr/ChangeLog:

	* configure: Regenerate.

sim/bfin/ChangeLog:

	* configure: Regenerate.

sim/common/ChangeLog:

	* acinclude.m4 (SIM_AC_COMMON) Honor existing CC_FOR_BUILD in
	environment.

sim/cr16/ChangeLog:

	* configure: Regenerate.

sim/cris/ChangeLog:

	* configure: Regenerate.

sim/d10v/ChangeLog:

	* configure: Regenerate.

sim/erc32/ChangeLog:

	* configure: Regenerate.

sim/frv/ChangeLog:

	* configure: Regenerate.

sim/ft32/ChangeLog:

	* configure: Regenerate.

sim/h8300/ChangeLog:

	* configure: Regenerate.

sim/iq2000/ChangeLog:

	* configure: Regenerate.

sim/lm32/ChangeLog:

	* configure: Regenerate.

sim/m32c/ChangeLog:

	* configure: Regenerate.

sim/m32r/ChangeLog:

	* configure: Regenerate.

sim/m68hc11/ChangeLog:

	* configure: Regenerate.

sim/mcore/ChangeLog:

	* configure: Regenerate.

sim/microblaze/ChangeLog:

	* configure: Regenerate.

sim/mips/ChangeLog:

	* configure: Regenerate.

sim/mn10300/ChangeLog:

	* configure: Regenerate.

sim/moxie/ChangeLog:

	* configure: Regenerate.

sim/msp430/ChangeLog:

	* configure: Regenerate.

sim/rl78/ChangeLog:

	* configure: Regenerate.

sim/rx/ChangeLog:

	* configure: Regenerate.

sim/sh/ChangeLog:

	* configure: Regenerate.

sim/sh64/ChangeLog:

	* configure: Regenerate.

sim/v850/ChangeLog:

	* configure: Regenerate.