Emit .note.GNU-stack for soft-float linux targets.

gcc/ChangeLog:

2020-01-23  Dragan Mladjenovic  <dmladjenovic@wavecomp.com>

	* config/mips/linux.h (NEED_INDICATE_EXEC_STACK): Define to
	TARGET_SOFT_FLOAT.
	* config/mips/mips.c (TARGET_ASM_FILE_END): Define to ...
	(mips_asm_file_end): New function. Delegate to
	file_end_indicate_exec_stack if NEED_INDICATE_EXEC_STACK is true.
	* config/mips/mips.h (NEED_INDICATE_EXEC_STACK): Define to 0.

libgcc/ChangeLog:

2020-01-23  Dragan Mladjenovic  <dmladjenovic@wavecomp.com>

	* config/mips/gnustack.h: New file.
	* config/mips/crti.S: Include gnustack.h.
	* config/mips/crtn.S: Likewise.
	* config/mips/mips16.S: Likewise.
	* config/mips/vr4120-div.S: Likewise.