feat(build): manage patch version in Makefile

Add VERSION_PATCH macro in Makefile. This will help LTS releases.
While at it, handle VERSION_PATCH macro in .versionrc.js script.

Change-Id: Id3ec359f7768a90ba5c67e35d29736a46eb402b5
Signed-off-by: Yann Gautier <yann.gautier@st.com>
diff --git a/.versionrc.js b/.versionrc.js
index 3a21ded..c7ee4a2 100644
--- a/.versionrc.js
+++ b/.versionrc.js
@@ -129,16 +129,19 @@
                 "readVersion": function (contents) {
                     const major = contents.match(/^VERSION_MAJOR\s*:=\s*(\d+?)$/m)[1];
                     const minor = contents.match(/^VERSION_MINOR\s*:=\s*(\d+?)$/m)[1];
+                    const patch = contents.match(/^VERSION_PATCH\s*:=\s*(\d+?)$/m)[1];
 
-                    return `${major}.${minor}.0`;
+                    return `${major}.${minor}.${patch}`;
                 },
 
                 "writeVersion": function (contents, version) {
                     const major = version.split(".")[0];
                     const minor = version.split(".")[1];
+                    const patch = version.split(".")[2];
 
                     contents = contents.replace(/^(VERSION_MAJOR\s*:=\s*)(\d+?)$/m, `$1${major}`);
                     contents = contents.replace(/^(VERSION_MINOR\s*:=\s*)(\d+?)$/m, `$1${minor}`);
+                    contents = contents.replace(/^(VERSION_PATCH\s*:=\s*)(\d+?)$/m, `$1${patch}`);
 
                     return contents;
                 }
diff --git a/Makefile b/Makefile
index 8e8fba9..6678179 100644
--- a/Makefile
+++ b/Makefile
@@ -9,7 +9,8 @@
 #
 VERSION_MAJOR			:= 2
 VERSION_MINOR			:= 9
-VERSION				:= ${VERSION_MAJOR}.${VERSION_MINOR}
+VERSION_PATCH			:= 0
+VERSION				:= ${VERSION_MAJOR}.${VERSION_MINOR}.${VERSION_PATCH}
 
 # Default goal is build all images
 .DEFAULT_GOAL			:= all