hppa64: Fallback to .text if .dynamic isn't found

Commit a1c2fa92ac93bf50227941bd82094e6997c5fd56 broke the ld
testcase for .note.GNU-stack wanting to be SHT_NOTE.  Fix this
by falling back to .text if .dynamic isn't available to define
the text segment base.

2026-01-21  John David Anglin  <danglin@gcc.gnu.org>

bfd/ChangeLog:

	* elf64-hppa.c (elf64_hppa_late_size_sections): Fallback
	to .text if .dynamic section isn't found.