Update scripts for new thirdparty convention

scripts/build_sokol_demo.ps1

@@ -44,7 +44,6 @@ $path_sokol_tools   = join-path $path_thirdparty 'sokol-tools'
 
 $sokol_build_clibs_command = join-path $path_scripts 'build_sokol_library.ps1'
 
-# clone-gitrepo $path_freetype    $url_freetype
 clone-gitrepo $path_sokol_tools $url_sokol_tools
 
 Update-GitRepo -path $path_sokol    -url $url_sokol     -build_command $sokol_build_clibs_command

scripts/helpers/misc.ps1

@@ -66,6 +66,10 @@ function Update-GitRepo
 		return
 	}
 	
+	if ( -not(test-path -Path (join-path $path '.git'))) {
+		return # Assume the user doesn't want to use git grab packages automatically.
+	}
+
 	git -C $path fetch
 	$latest_commit_hash = git -C $path rev-parse '@{u}'
 	$last_built_hash    = if (Test-Path $last_built_commit) { Get-Content $last_built_commit } else { "" }