build: require gcc >= 5.3 and switch to C++14

Change-Id: I53ecd93b5666f451129afbe7ba02de357218efb5
Refs: #4462, #3076
diff --git a/.jenkins.d/README.md b/.jenkins.d/README.md
index 41812aa..39fa40b 100644
--- a/.jenkins.d/README.md
+++ b/.jenkins.d/README.md
@@ -13,13 +13,13 @@
 
   * `[OS_TYPE]`: `Linux`
   * `[DISTRO_TYPE]`: `Ubuntu`
-  * `[DISTRO_VERSION]`: `Ubuntu-14.04`, `Ubuntu-16.04`
+  * `[DISTRO_VERSION]`: `Ubuntu-16.04`, `Ubuntu-18.04`
 
   Possible values for OS X / macOS:
 
   * `[OS_TYPE]`: `OSX`
   * `[DISTRO_TYPE]`: `OSX` (can be absent)
-  * `[DISTRO_VERSION]`: `OSX-10.10`, `OSX-10.11`, `OSX-10.12`
+  * `[DISTRO_VERSION]`: `OSX-10.11`, `OSX-10.12`, `OSX-10.13`
 
 - `JOB_NAME`: optional variable to define type of the job.  Depending on the defined job type,
   the build scripts can perform different tasks.