autotools: Add code coverage support

Change-Id: I7d11c64ffa3e68973081cfb1f3fdc1817a64e8cd
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
diff --git a/configure.ac b/configure.ac
index ced6911..c4f778f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -42,6 +42,8 @@
     AC_SUBST([OESDK_TESTCASE_FLAGS], [$testcase_flags])
 )
 
+AX_CODE_COVERAGE
+
 PKG_CHECK_MODULES(LIBSYSTEMD, libsystemd, , AC_MSG_ERROR([libsytemd not found]))
 AC_SUBST([LIBSYSTEMD_CFLAGS])
 AC_SUBST([LIBSYSTEMD_LIBS])