Respect a possibly prefixed readelf

...i case of cross-compiling. Already done for other tests with
07bbf47.

(cherry picked from commit d0c418f)

Author: heirecka

tests/repeated-updates.sh

@@ -2,6 +2,7 @@
 
 SCRATCH=scratch/$(basename "$0" .sh)
 PATCHELF=$(readlink -f "../src/patchelf")
+READELF=${READELF:-readelf}
 
 rm -rf "${SCRATCH}"
 mkdir -p "${SCRATCH}"
@@ -18,7 +19,7 @@ ${PATCHELF} --add-needed ./libbar.so simple
 # Test that repeatedly modifying a string inside a shared library does not
 # corrupt it due to the addition of multiple PT_LOAD entries
 ###############################################################################
-load_segments_before=$(readelf -W -l libbar.so | grep -c LOAD)
+load_segments_before=$(${READELF} -W -l libbar.so | grep -c LOAD)
 
 for _ in $(seq 1 100)
 do
@@ -27,7 +28,7 @@ do
     ./simple || exit 1
 done
 
-load_segments_after=$(readelf -W -l libbar.so | grep -c LOAD)
+load_segments_after=$(${READELF} -W -l libbar.so | grep -c LOAD)
 
 ###############################################################################
 # To be even more strict, check that we don't add too many extra LOAD entries