Use run_host_cmd to run $CC and other no-section-header test fixes

Use run_host_cmd to run $CC and other no-section-header test fixes

We should be using run_host_cmd everywhere we invoke a compiler in the
ld testsuite, if we want to use ld/ld-new just built.  run_host_cmd
properly inserts $gcc_B_opt in cases where a user wants to test
binutils with a newly built compiler, ie. when $CC specifies -B itself.

Also, it is not good practice to exclude tests when non-native except
of course those tests that run a target binary.  Compiling and linking
often shows up problems.

	* testsuite/ld-elf/no-section-header.exp (binutils_run_test):
	Use run_host_cmd to invoke $CC_FOR_TARGET.  Run all tests
	non-native too, except for attempting to run the binaries.
	Run tests for ELF in general, not just linux.
	* testsuite/ld-elf/pr25617-1-no-sec-hdr.rd: Allow localentry
	symbol decoration, and support either sorting of symbols.
	* testsuite/ld-elf/pr25617-1a-no-sec-hdr.rd: Likewise.
	* testsuite/ld-elf/pr25617-1a-sec-hdr.rd: Likewise.
	* testsuite/ld-elf/pr25617-1a-no-sec-hdr.nd: Accept D function syms.
	* testsuite/ld-elf/start-shared-noheader-sysv.rd: Accept
	mips-sgi-irix symbol output.
	* testsuite/ld-elf/start-shared-noheader.nd: Likewise.