elfutils: remove unused variables to fix compilation with GCC 4.6

Unused variables trigger a warning in GCC 4.6 which are caught by -Werror as
used in the elfutils makefiles and therefore the build fails.

This patch adds some consolidated fixes from upstream to remove the unused
variables, they will no longer be required as of elfutils 0.152

Signed-off-by: Joshua Lock <josh@linux.intel.com>

meta/recipes-devtools/elfutils/elfutils_0.148.bb

@@ -6,7 +6,7 @@ LIC_FILES_CHKSUM = "file://COPYING;md5=0636e73ff0215e8d672dc4c32c317bb3\
                     file://EXCEPTION;md5=570adcb0c1218ab57f2249c67d0ce417"
 DEPENDS = "libtool bzip2 zlib"
 
-PR = "r1"
+PR = "r2"
 
 SRC_URI = "https://fedorahosted.org/releases/e/l/elfutils/elfutils-${PV}.tar.bz2"
 
@@ -27,6 +27,7 @@ SRC_URI += "\
         file://testsuite-ignore-elflint.diff \
         file://elf_additions.diff \
 	file://elfutils-fsize.patch \
+	file://remove-unused.patch \
 "
 
 # The buildsystem wants to generate 2 .h files from source using a binary it just built,