Force dumpvars into dumb terminal mode and move log files

Force soong_ui in dumpvars mode to use a dumb terminal so that it
doesn't print an empty status table.  Also move the logs to files
that are prefixed with "dumpvars-" so that they don't rotate the
real build logs.

Fixes: 139307849
Test: lunch
Change-Id: If92421af07731fedc9ca42670f309e95922a2224
diff --git a/ui/terminal/status.go b/ui/terminal/status.go
index 69a2a09..60dfc70 100644
--- a/ui/terminal/status.go
+++ b/ui/terminal/status.go
@@ -26,10 +26,10 @@
 //
 // statusFormat takes nearly all the same options as NINJA_STATUS.
 // %c is currently unsupported.
-func NewStatusOutput(w io.Writer, statusFormat string, quietBuild bool) status.StatusOutput {
+func NewStatusOutput(w io.Writer, statusFormat string, forceDumbOutput, quietBuild bool) status.StatusOutput {
 	formatter := newFormatter(statusFormat, quietBuild)
 
-	if isSmartTerminal(w) {
+	if !forceDumbOutput && isSmartTerminal(w) {
 		return NewSmartStatusOutput(w, formatter)
 	} else {
 		return NewDumbStatusOutput(w, formatter)