Please backport fix for Fedora bz 1691822.

Copying its description below:

Kernel's rpm build process executes this command at a certain stage:

/usr/lib/rpm/brp-strip-static-archive /usr/bin/strip

which is a shell script.

At this point, kernel build tree has ~60 thousand files. Even though our build machines have at least 6-10 CPUs, the script is written so that it executes "file FILE" for every file, in sequence:

# Strip static libraries.
for f in `find "$RPM_BUILD_ROOT" -type f -a -exec file {} \; | \
        grep -v "^${RPM_BUILD_ROOT}/\?usr/lib/debug"  | \
        grep 'current ar archive' | \
        sed -n -e 's/^\(.*\):[  ]*current ar archive/\1/p'`; do
        $STRIP -g "$f"
done

This means one fork per file. And totally sequential. For kernel, this takes 2 minutes on a fast x86 machine with 88 CPUs.

Proposed replacement:

# Strip static libraries.
#
# Sometimes this is run on trees with 100 thousand files. Be efficient:
# xargs -r -P$NPROC -n16 file | sed 's/:  */: /'
# is used to
# * xargs: avoid fork overhead per each file
# * -P$NPROC: parallelize
# * -n16: avoid running just a few "file LIST" cmds with huge LISTs
# * sed 's/:  */: /': defeat "file F1 FILE2" columnar formatting:
#   | F1:    type1 <--- extra spaces after colon
#   | FILE2: type2
NPROC=`nproc`
test "$NPROC" || NPROC=1
for f in `find "$RPM_BUILD_ROOT" -type f | \
        grep -v "^${RPM_BUILD_ROOT}/\?usr/lib/debug" | \
        xargs -r -P$NPROC -n16 file | sed 's/:  */: /' | \
        grep 'current ar archive' | \
        sed -n -e 's/^\(.*\):[  ]*current ar archive/\1/p'`; do
        $STRIP -g "$f"
done

For kernel build, this reduces time to run this fragment from 2 minutes to 3 seconds on a 88 CPU machine.