PR26822, How to prevent a STT_FILE with absolute path in the linked image

bfd/
	PR 26822
	* elflink.c (elf_link_input_bfd): Use the file base name in
	linker generated STT_FILE symbols.
ld/
	PR 26822
	* testsuite/ld-arm/non-contiguous-arm2.d: Adjust STT_FILE symbol match.
	* testsuite/ld-arm/non-contiguous-arm3.d: Likewise.
	* testsuite/ld-arm/non-contiguous-arm5.d: Likewise.
	* testsuite/ld-arm/non-contiguous-arm6.d: Likewise.
	* testsuite/ld-i386/tlsbin.rd: Likewise.
	* testsuite/ld-i386/tlsbin2.rd: Likewise.
	* testsuite/ld-i386/tlsbindesc.rd: Likewise.
	* testsuite/ld-i386/tlsdesc.rd: Likewise.
	* testsuite/ld-i386/tlsnopic.rd: Likewise.
	* testsuite/ld-i386/tlspic.rd: Likewise.
	* testsuite/ld-i386/tlspic2.rd: Likewise.
	* testsuite/ld-mips-elf/global-local-symtab-sort-n64.d: Likewise.
	* testsuite/ld-mips-elf/global-local-symtab-sort-n64t.d: Likewise.
	* testsuite/ld-mips-elf/global-local-symtab-sort-o32.d: Likewise.
	* testsuite/ld-mips-elf/global-local-symtab-sort-o32t.d: Likewise.
	* testsuite/ld-plugin/pr17973.d: Likewise.
	* testsuite/ld-tic6x/shlib-1.rd: Likewise.
	* testsuite/ld-tic6x/shlib-1b.rd: Likewise.
	* testsuite/ld-tic6x/shlib-1r.rd: Likewise.
	* testsuite/ld-tic6x/shlib-1rb.rd: Likewise.
	* testsuite/ld-tic6x/shlib-app-1.rd: Likewise.
	* testsuite/ld-tic6x/shlib-app-1b.rd: Likewise.
	* testsuite/ld-tic6x/shlib-app-1r.rd: Likewise.
	* testsuite/ld-tic6x/shlib-app-1rb.rd: Likewise.
	* testsuite/ld-tic6x/shlib-noindex.rd: Likewise.
	* testsuite/ld-tic6x/static-app-1.rd: Likewise.
	* testsuite/ld-tic6x/static-app-1b.rd: Likewise.
	* testsuite/ld-tic6x/static-app-1r.rd: Likewise.
	* testsuite/ld-tic6x/static-app-1rb.rd: Likewise.
	* testsuite/ld-x86-64/tlsbin.rd: Likewise.
	* testsuite/ld-x86-64/tlsbin2.rd: Likewise.
	* testsuite/ld-x86-64/tlsbindesc.rd: Likewise.
	* testsuite/ld-x86-64/tlsdesc.rd: Likewise.
	* testsuite/ld-x86-64/tlspic.rd: Likewise.
	* testsuite/ld-x86-64/tlspic2.rd: Likewise.
	* testsuite/ld-xtensa/tlsbin.rd: Likewise.
	* testsuite/ld-xtensa/tlspic.rd: Likewise.