Fix automake not to replace Fedora compiler flags.

Author: Jan Vcelak <jvcelak@redhat.com>

diff -u a/common/build/pion-setup.inc b/common/build/pion-setup.inc
--- a/common/build/pion-setup.inc
+++ b/common/build/pion-setup.inc
@@ -86,9 +86,9 @@ case "$build_os" in
 	# Other (Linux): GCC compiler
 	CPPFLAGS="$CPPFLAGS -pthread -D_REENTRANT"
 	LDFLAGS="$LDFLAGS -pthread -Wl,-E"
-	PION_OPT_FLAGS="-O2 -ggdb -Wall -Wno-strict-aliasing -DNDEBUG"
-	PION_DEBUG_FLAGS="-O0 -ggdb -Wall -Wno-strict-aliasing -fkeep-inline-functions"
-	PION_EXTERNAL_LIBS="-ldl -licui18n -licuuc -licudata"
+	PION_OPT_FLAGS="-Wall -Wno-strict-aliasing -DNDEBUG"
+	PION_DEBUG_FLAGS="-O0 -Wall -Wno-strict-aliasing -fkeep-inline-functions"
+	PION_EXTERNAL_LIBS=""
 	;;
 esac
 
diff -u a/configure.ac b/configure.ac
--- a/configure.ac
+++ b/configure.ac
@@ -23,10 +23,8 @@ DX_DOXYGEN_FEATURE(ON)
 DX_HTML_FEATURE(ON)
 DX_INIT_DOXYGEN(pion-net, net/doc/Doxyfile, net/doc)
 
-# Define CXXFLAGS before AC_PROG_CXX to suppress the default autoconf
-# compiler options
-CFLAGS="-DPION_NETWORK_LIBRARY"
-CXXFLAGS="-DPION_NETWORK_LIBRARY"
+CFLAGS="$CFLAGS -DPION_NETWORK_LIBRARY"
+CXXFLAGS="$CXXFLAGS -DPION_NETWORK_LIBRARY"
 
 # Currently only the embedded common library can be used
 PION_COMMON_HOME=`pwd`/common