backport: re PR lto/81487 ([mingw32] ld.exe: error: asprintf failed)

backport: re PR lto/81487 ([mingw32] ld.exe: error: asprintf failed)

lto-plugin/
	Backport from 2017-07-26 gcc-7-branch r250562.
	PR lto/81487
	* lto-plugin.c (claim_file_handler): Use xasprintf instead of
	asprintf.
	[hi!=0]: Swap hi and lo arguments supplied to xasprintf.
gcc/
	Backport from 2017-07-26 gcc-7-branch r250562.
	PR 81487
	* hsa-brig.c (brig_init): Use xasprintf instead of asprintf.
	* tree-ssa-structalias.c (alias_get_name): Same.

From-SVN: r250573