[AArch64] Fall back to -fPIC if no support of -fpic in binutils

[AArch64] Fall back to -fPIC if no support of -fpic in binutils

2015-07-01  Jiong Wang  <jiong.wang@arm.com>

	* configure.ac: Add check for aarch64 assembler -fpic relocation
	modifier support.
	* configure: Regenerate.
	* config.in: Regenerate.
	* config/aarch64/aarch64.c (initialize_aarch64_code_model): Fall back
	to -fPIC if not support of -fpic relocation modifier in assembler.

From-SVN: r225231