scripts: add local version number file

we now using git tag for version number control, but if
we release the code without .git/ folder, the git tag version
number is not present, so will cause compile error.
add the .tarball-version file as the local version number file,
it still can be generated by the autogen.sh from git tag. So
everytime anyone make a git tag should still modify the
.tarball-version file.

Signed-off-by: Zhu Yingjiang <yingjiang.zhu@linux.intel.com>

.gitignore

@@ -15,7 +15,6 @@
 *.rom
 *.man
 .version
-.tarball-version
 *.x
 .build
 *.dis

.tarball-version

@@ -0,0 +1 @@
+v1.1-185-g3507

version.sh

@@ -15,14 +15,18 @@ fi
 GIT_TAG=`git describe --abbrev=4 2>/dev/null`
 
 # may fail to get git describe in some case, add this fallback to handle error
-if [[ "x$GIT_TAG" == "x" ]]
-then
-	GIT_TAG="v0.0-0-g0000"
+if [[ "x$GIT_TAG" == "x" ]]; then
+        if  [ -e $DIR/.tarball-version ]; then
+                VER=$(cat $DIR/.tarball-version)
+                echo $VER > $DIR/.version
+        else
+		GIT_TAG="v0.0-0-g0000"
+	fi
 fi
 
 # Some releases have a SOF_FW_XXX_ prefix on the tag and this prefix
 # must be stripped for usage in version.h. i.e. we just need the number.
-if [ $(expr match $GIT_TAG 'SOF_FW_[A-Z]+_' ) -lt 15 ]; then
+if [ $(expr match "$GIT_TAG" 'SOF_FW_[A-Z]+_' ) -lt 15 ]; then
 	VER=`echo $GIT_TAG | cut -d_ -f4`
 else
 	VER=$GIT_TAG