debuginfo: Fix processing of hard-linked binaries

while-end output into the pipe forgets all set inside variables.

Error message:

  ln: .debuginfo/src/: hard link not allowed for directory

scripts/brp-debuginfo.in

@@ -45,8 +45,10 @@ while read -r nlink ino f; do
 	fi
 	printf '%s\n' "$f"
 done <.tmp/flist \
-    3>.tmp/link-list \
-     | xargs -r -P$(nproc) -n1 @RPMCONFIGDIR@/process-debuginfo
+     >.tmp/xargs-list \
+    3>.tmp/link-list
+
+xargs -r -P$(nproc) -n1 @RPMCONFIGDIR@/process-debuginfo <.tmp/xargs-list
 
 # Hard-link debuginfo for hard-linked binaries
 while read -r ino f; do