ld: Use [list ] syntax to define run_tests in indirect.exp

ld: Use [list ] syntax to define run_tests in indirect.exp

Currently, the var run_tests is defined by syntax {{}},
while in this case, variables cannot be used.
Thus $NOPIE_CFLAGS and $NOPIE_LDFLAGS are passed to cmd as names
instead of values:
  gcc ... $NOPIE_CFLAGS -c .../indirect5a.c -o tmpdir/indirect5a.o

Let's use [list [list ]] syntax instead.

ld/ChangeLog:

	* testsuite/ld-elf/indirect.exp(run_tests): use [list [list]]
	syntax instead of {{}}.

(cherry picked from commit 96a73f2cb2a1b4c47e49ff194a94f7394308956b)