[PR ld/25062] arm: sign extend the addend of R_ARM_TLS_GOTDESC

On 64-bit host the 32-bit addend was loaded without sign extension into
an unsigned long.

bfd/ChangeLog:

	PR ld/25062
	* elf32-arm.c (elf32_arm_final_link_relocate): Sign extend data.

ld/ChangeLog:

	PR ld/25062
	* testsuite/ld-arm/arm-elf.exp: Update.
	* testsuite/ld-arm/tls-gdesc-neg.d: New test.
	* testsuite/ld-arm/tls-gdesc-neg.s: New test.