[PATCH for-4.21] tools/tests: don't pass -E to sed

[Jan Beulich <jbeulich@suse.com>]

Even the 2018 edition of The Open Group Base Specifications Issue 7 [1]
doesn't name -E as a standard option; only Issue 8 [2] does. As there's
nothing "extended" about the expression used, simply drop the -E.

[1] https://pubs.opengroup.org/onlinepubs/9699919799/
[2] https://pubs.opengroup.org/onlinepubs/9799919799/

Fixes: cb50e4033717 ("test/pdx: add PDX compression unit tests")
Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
In principle the -e could be dropped too, for being redundant.

Hitting the problem with an older sed pointed out another problem here as
well: The failed invocation left a 0-byte pdx.h, which upon re-invocation
of make was (obviously) deemed up-to-date, thus causing the build to fail
again (until the bad file was actually removed).

--- a/tools/tests/pdx/Makefile
+++ b/tools/tests/pdx/Makefile
@@ -35,7 +35,7 @@ uninstall:
 	$(RM) -- $(patsubst %,$(DESTDIR)$(LIBEXEC)/tests/%,$(TARGETS))
 
 pdx.h: $(XEN_ROOT)/xen/include/xen/pdx.h
-	sed -E -e '/^#[[:space:]]*include/d' <$< >$@
+	sed -e '/^#[[:space:]]*include/d' <$< >$@
 
 CFLAGS += -D__XEN_TOOLS__
 CFLAGS += $(APPEND_CFLAGS)