Disable --eh-frame-hdr with -pie or -shared on nios2-linux-gnu.

Disable --eh-frame-hdr with -pie or -shared on nios2-linux-gnu.

2019-12-05  Sandra Loosemore  <sandra@codesourcery.com>

	Disable --eh-frame-hdr with -pie or -shared on nios2-linux-gnu.

	The nios2 ABI doesn't have appropriate relocations to support
	--eh-frame-hdr with -pie or -shared, so we need to override the
	default specs that add that link option.  Otherwise we get linker
	warnings about invalid FDE encodings.

	gcc/
	* config/nios2/linux.h (LINK_EH_SPEC): Define.

	gcc/testsuite/
	* g++.target/nios2/hello-pie.C: New.
	* g++.target/nios2/nios2.exp: New.

From-SVN: r279023