Passing $ax_is_release is not only unnecessary (the related macros already
use it by default), but wrong as it causes an invalid configuration test
define to be generated.

file upstream bug

--- yelp-3.16.1/configure.ac	2015-05-11 10:33:26.000000000 -0700
+++ yelp-3.16.1/configure.ac	2015-07-02 21:59:51.040121647 -0700
@@ -11,9 +11,9 @@
 AM_SILENT_RULES([yes])
 
 AX_IS_RELEASE([git-directory])
-AX_CHECK_ENABLE_DEBUG([info], [YELP_DEBUG], [$ax_is_release])
+AX_CHECK_ENABLE_DEBUG([info], [YELP_DEBUG])
 
-AX_COMPILER_FLAGS([], [], [$ax_is_release])
+AX_COMPILER_FLAGS()
 # Check for programs
 AC_PROG_CC
 AC_PROG_CC_C_O