Force C++14 for configure step too

ppc64-diag.spec

@@ -1,6 +1,6 @@
 Name:           ppc64-diag
 Version:        2.7.6
-Release:        7%{?dist}
+Release:        8%{?dist}
 Summary:        PowerLinux Platform Diagnostics
 URL:            https://github.com/power-ras/%{name}
 License:        GPLv2
@@ -59,7 +59,7 @@ This package contains only rtas_errd daemon.
 
 %build
 ./autogen.sh
-%configure
+CXXFLAGS="-std=gnu++14 %{build_cflags}" %configure
 LDFLAGS="%{build_ldflags}" CFLAGS="%{build_cflags}" CXXFLAGS="-std=gnu++14 %{build_cflags}" make %{?_smp_mflags} V=1
 
 %install
@@ -169,6 +169,9 @@ if [ "$1" = "0" ]; then # last uninstall
 fi
 
 %changelog
+* Tue Oct 27 2020 Jeff Law <law@redhat.com> - 2.7.6-8
+- Force C++14 for configure step too
+
 * Tue Oct 27 2020 Jeff Law <law@redhat.com> - 2.7.6-7
 - Force C++14 mode as this code is not C++17 ready