libcap: clean up gperf enabling logic

There's no need to sed the Makefile (especially the wrong Makefile) when there's
a variable we can pass.

(From OE-Core rev: 43f7652baa0f1973477731ce05786eda2cc81c09)

Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-support/libcap/libcap_2.25.bb

@@ -22,9 +22,6 @@ do_configure() {
 	# on what should be replaced with ?=
 	sed -e 's,:=,?=,g' -i Make.Rules
 	sed -e 's,^BUILD_CFLAGS ?= $(.*CFLAGS),BUILD_CFLAGS := $(BUILD_CFLAGS),' -i Make.Rules
-
-	# disable gperf detection
-	sed -e '/shell gperf/cifeq (,yes)' -i libcap/Makefile
 }
 
 PACKAGECONFIG ??= "${@bb.utils.filter('DISTRO_FEATURES', 'pam', d)}"
@@ -37,6 +34,7 @@ EXTRA_OEMAKE = " \
   lib=${@os.path.basename('${libdir}')} \
   RAISE_SETFCAP=no \
   DYNAMIC=yes \
+  BUILD_GPERF=yes \
 "
 
 EXTRA_OEMAKE_append_class-target = " SYSTEM_HEADERS=${STAGING_INCDIR}"