Revert "t/test_lib: avoid naked bash arrays in file_lineno"

This reverts commit 303775a25f0b4ac5d6ad2e96eb4404c24209cad8;
instead of trying to salvage the tap-breaking change, let's
revert the whole thing for now.

t/test-lib.sh

@@ -677,7 +677,6 @@ die () {
 
 file_lineno () {
 	test -z "$GIT_TEST_FRAMEWORK_SELFTEST" && test -n "$BASH" || return 0
-	eval '
 	local i
 	for i in ${!BASH_SOURCE[*]}
 	do
@@ -686,7 +685,6 @@ file_lineno () {
 		*,t[0-9]*.sh) echo "t/${BASH_SOURCE[$i]}:${BASH_LINENO[$(($i-1))]}: ${1+$1: }"; return;;
 		esac
 	done
-	'
 }
 
 GIT_EXIT_OK=