autoPatchelfHook: Skip on missing segment headers

If the file in question is not a shared object file but an ELF, we
really want to skip the file, because we won't have anything to patch
there.

For example if the file is created via "gcc -c -o foo.o foo.c", we don't
get a segment header and so far autoPatchelf was trying to patch such a
file.

By checking for missing segment headers, we're now no longer going to
attempt patching such a file.

Signed-off-by: aszlig <aszlig@nix.build>
Reported-by: Sander van der Burg <svanderburg@gmail.com>

pkgs/build-support/setup-hooks/auto-patchelf.sh

@@ -205,9 +205,12 @@ autoPatchelf() {
     # outside of this function.
     while IFS= read -r -d $'\0' file; do
       isELF "$file" || continue
+      segmentHeaders="$(LANG=C readelf -l "$file")"
+      # Skip if the ELF file doesn't have segment headers (eg. object files).
+      echo "$segmentHeaders" | grep -q '^Program Headers:' || continue
       if isExecutable "$file"; then
           # Skip if the executable is statically linked.
-          LANG=C readelf -l "$file" | grep -q "^ *INTERP\\>" || continue
+          echo "$segmentHeaders" | grep -q "^ *INTERP\\>" || continue
       fi
       autoPatchelfFile "$file"
     done < <(find "$@" ${norecurse:+-maxdepth 1} -type f -print0)