vboot: remove -drop-ld-preload from qemu invocation

This flag is currently not supported in the qemu binary,
and causes qemu process to end with a return code of 1,
making all tests fail.

The inability to enable this flag is likely the cause
of all the warnings in test output:

  ERROR: ld.so: object 'libsandbox.so' from LD_PRELOAD
  cannot be preloaded (cannot open shared object file): ignored.

BUG=b:124141368, chromium:605348
TEST=make clean && make runtests
TEST=force QEMU_ARCH := ${ARCH} and run:
     FEATURES=test emerge-eve vboot_reference
BRANCH=none

Change-Id: Ie8c06da7a52638268d6ab318b591c995b18b98b3
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/2050969
Tested-by: Joel Kitching <kitching@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Joel Kitching <kitching@chromium.org>
diff --git a/tests/test_using_qemu.sh b/tests/test_using_qemu.sh
index 6b3f073..081d963 100755
--- a/tests/test_using_qemu.sh
+++ b/tests/test_using_qemu.sh
@@ -24,7 +24,7 @@
 
 # Don't exit on error, so we can capture the error code
 set +e
-sudo chroot ${SYSROOT} ${QEMU_RUN} -drop-ld-preload \
+sudo chroot ${SYSROOT} ${QEMU_RUN} \
     -E LD_LIBRARY_PATH=/lib64:/lib:/usr/lib64:/usr/lib \
     -E HOME=${HOME} \
     -E BUILD=${BUILD_RUN} \