Simplify exit status fix, restore interruptability

The exit status fix introduced in cherry-picked commit 22c3a6e1
introduced a problem: interrupting the build only interrupted the
main process, and the background job would happily continue.

bin/package, src/cmd/INIT/package.sh:
- Give up on the idea of a background job and put up with not
  cleaning up the FIFO. It's in a build directory that is going to
  get cleaned up anyway.

bin/package

@@ -3969,6 +3969,8 @@ capture() # file command ...
 		0)	if	executable ! $TEE
 			then	TEE=tee
 			fi
+			# Connect 'tee' to a FIFO instead of a pipe, so that the build is invoked from
+			# the main shell environment and its exit status can be used for $error_status
 			rm -f $o.fifo
 			mkfifo -m 600 $o.fifo || exit
 			$TEE -a $o < $o.fifo &
@@ -3978,9 +3980,7 @@ capture() # file command ...
 				esac
 				showenv $action
 				"$@"
-			} > $o.fifo 2>&1 &
-			rm $o.fifo 	# unlink early
-			wait "$!"	# get build's exit status
+			} < /dev/null > $o.fifo 2>&1
 			;;
 		*)	{
 				case $s in

src/cmd/INIT/package.sh

@@ -3968,6 +3968,8 @@ capture() # file command ...
 		0)	if	executable ! $TEE
 			then	TEE=tee
 			fi
+			# Connect 'tee' to a FIFO instead of a pipe, so that the build is invoked from
+			# the main shell environment and its exit status can be used for $error_status
 			rm -f $o.fifo
 			mkfifo -m 600 $o.fifo || exit
 			$TEE -a $o < $o.fifo &
@@ -3977,9 +3979,7 @@ capture() # file command ...
 				esac
 				showenv $action
 				"$@"
-			} > $o.fifo 2>&1 &
-			rm $o.fifo 	# unlink early
-			wait "$!"	# get build's exit status
+			} < /dev/null > $o.fifo 2>&1
 			;;
 		*)	{
 				case $s in