Fix coverity

Author: peternewman

Makefile.am

@@ -34,4 +34,3 @@ include tests/Makefile.mk
 include tools/Makefile.mk
 
 check_PROGRAMS = $(TESTS)
-

configure.ac

@@ -11,6 +11,7 @@ AC_LANG_PUSH([C++])
 
 # Checks for programs.
 AC_PROG_CXX
+AC_PROG_CC
 
 # Checks for libraries.
 
@@ -20,6 +21,9 @@ AC_PROG_LIBTOOL
 # Check we have -std=c++11 support
 AX_CXX_COMPILE_STDCXX_11(noext,mandatory)
 
+# Switch the C compiler into C99 mode
+AC_PROG_CC_C99
+
 # Checks for header files.
 AC_CHECK_HEADERS([arpa/inet.h stdint.h stdlib.h string.h])