Make linker assigned symbol dynamic only for shared object

Make linker assigned symbol dynamic only for shared object

Linker assigned symbols should be made dynamic by default only when
creating shared object or relocatable executable.

bfd/

	* elflink.c (bfd_elf_record_link_assignment): Check for shared
	library, instead of PIC, and don't check PDE when making linker
	assigned symbol dynamic.

ld/

	* testsuite/ld-frv/fdpic-pie-6.d: Updated.
	* testsuite/ld-mips-elf/pie-n32.d: Likewise.
	* testsuite/ld-mips-elf/pie-n64.d: Likewise.
	* testsuite/ld-mips-elf/pie-o32.d: Likewise.