COMPMID-1246: Always re-generate arm_compute_version.embed

- This won't trigger a rebuild of the library if the file is unchanged (i.e SCons does a checksum after the file is generated)
- This fix the issue when build options or a commit changes and the file isn't updated

Change-Id: Ic1d0f5435960b4c50b07b54484b660d6f8ce3f71
Reviewed-on: https://eu-gerrit-1.euhpc.arm.com/145540
Reviewed-by: Michele DiGiorgio <michele.digiorgio@arm.com>
Tested-by: Jenkins <bsgcomp@arm.com>
diff --git a/SConscript b/SConscript
index 7b0753d..36fa7b6 100644
--- a/SConscript
+++ b/SConscript
@@ -118,15 +118,16 @@
     except (OSError, subprocess.CalledProcessError):
         git_hash="unknown"
 
-    version_filename = "%s/arm_compute_version.embed" % Dir("src/core").path
     build_info = "\"arm_compute_version=%s Build options: %s Git hash=%s\"" % (VERSION, vars.args, git_hash.strip())
     with open(target[0].get_path(), "w") as fd:
         fd.write(build_info)
 
 arm_compute_env = env.Clone()
+version_file = arm_compute_env.Command("src/core/arm_compute_version.embed", "", action=create_version_file)
+arm_compute_env.AlwaysBuild(version_file)
 
 # Generate embed files
-generate_embed = [ arm_compute_env.Command("src/core/arm_compute_version.embed", "", action=create_version_file) ]
+generate_embed = [ version_file ]
 if env['opencl'] and env['embed_kernels']:
     cl_files = Glob('src/core/CL/cl_kernels/*.cl')
     cl_files += Glob('src/core/CL/cl_kernels/*.h')