[master] Disable strict aliasing rules for gcc < 4.5

This is a workaround for a GCC bug which affects gcc 4.4 and
manifests on RHEL6.3 as a build failure. This fix was okayed
on jabber.

configure.ac

@@ -182,6 +182,14 @@ AC_SUBST(WARNING_NO_MISSING_FIELD_INITIALIZERS_CFLAG)
 if test "X$GXX" = "Xyes"; then
 CXX_VERSION=`$CXX --version 2> /dev/null | head -1`
 KEA_CXXFLAGS="$KEA_CXXFLAGS -Wall -Wextra -Wnon-virtual-dtor -Wwrite-strings -Woverloaded-virtual -Wno-sign-compare"
+# gcc 4.4 would emit warnings about breaking strict aliasing rules.
+# See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=41874
+CXX_DUMP_VERSION=`$CXX -dumpversion | cut -f1-2 -d.`
+if test "$CXX_DUMP_VERSION" \< "4.5"; then
+       WARNING_GCC_44_STRICT_ALIASING_CFLAG="-fno-strict-aliasing"
+fi
+AC_SUBST(WARNING_GCC_44_STRICT_ALIASING_CFLAG)
+
 case "$host" in
 *-solaris*)
 	MULTITHREADING_FLAG=-pthreads

src/lib/eval/Makefile.am

@@ -10,6 +10,13 @@ AM_CXXFLAGS = $(KEA_CXXFLAGS)
 # But older GCC compilers don't have the flag.
 AM_CXXFLAGS += $(WARNING_NO_MISSING_FIELD_INITIALIZERS_CFLAG)
 
+# GCC 4.4 emits warning about breaking strict aliasing rule.
+# This warning is a result of a GCC bug:
+# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=41874
+# The warning is raised in the generated code in parser.h.
+# Disabling the strict aliasing rule suppresses this warning.
+AM_CXXFLAGS += $(WARNING_GCC_44_STRICT_ALIASING_CFLAG)
+
 lib_LTLIBRARIES = libkea-eval.la
 libkea_eval_la_SOURCES  =
 libkea_eval_la_SOURCES += eval_log.cc eval_log.h