sparc: Compile TLS LD tests with -fPIC

sparc: Compile TLS LD tests with -fPIC

After

commit 8cad8f94b450be9b73d07bdeef7fa1778d3f2b96
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Fri Sep 5 15:40:51 2025 -0700

    c: Update TLS model after processing a TLS variable

GCC will upgrade local-dynamic TLS model to local-exec without -fPIC.
Compile TLS LD tests with -fPIC to keep local-dynamic TLS model.

	PR testsuite/121888
	* gcc.target/sparc/tls-ld-int16.c: Compile with -fPIC.
	* gcc.target/sparc/tls-ld-int32.c: Likewise.
	* gcc.target/sparc/tls-ld-int64.c: Likewise.
	* gcc.target/sparc/tls-ld-int8.c: Likewise.
	* gcc.target/sparc/tls-ld-uint16.c: Likewise.
	* gcc.target/sparc/tls-ld-uint32.c: Likewise.
	* gcc.target/sparc/tls-ld-uint8.c: Likewise.

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>