Add short_call function attribute for MIPS

Add short_call function attribute for MIPS

gcc/
	* config/mips/mips.c (mips_attribute_table): Add 'short_call'
	attribute.
	(mips_near_type_p): Add 'short_call' attribute as a synonym
	for 'near'.
	* doc/extend.texi (short_call): Document new function attribute.

gcc/testsuite

	* gcc.target/mips/near-far-1.c: Add check for 'short_call'
	attribute.
	* gcc.target/mips/near-far-2.c: Likewise.
	* gcc.target/mips/near-far-3.c: Likewise.
	* gcc.target/mips/near-far-4.c: Likewise.

From-SVN: r252006