Bump C++ version from C++11 to C++14.

Signed-off-by: Vladimir Krivopalov <vlkrivop@microsoft.com>

BUILD.md

@@ -93,6 +93,6 @@ The steps below are for Ubuntu 16.04 LTS.
  5.  Configure and build ModSecurity:
 	 ```bash
 	 ./autogen.sh
-	 ./configure LDFLAGS=-g  CXXFLAGS="-std=c++11 " CFLAGS="-fPIC " --enable-standalone-module --disable-mlogc --enable-waf_json_logging
+	 ./configure LDFLAGS=-g  CXXFLAGS="-std=c++14 " CFLAGS="-fPIC " --enable-standalone-module --disable-mlogc --enable-waf_json_logging
 	 make
 	 ```

docker-compose.yaml

@@ -21,7 +21,7 @@ services:
     working_dir: /microsoft/modsecurity
     entrypoint: 
       - ./configure
-      - CXXFLAGS=-std=c++11
+      - CXXFLAGS=-std=c++14
       - CFLAGS=-fPIC
       - --enable-standalone-module
       - --disable-mlogc