Regres: Write logs to /dev/null

There's no point writing these to disk, we just overwrite them with the next test.
Unfortunately there's no way to actually disable writing these files.

Think green! Save a SSD!

Change-Id: Ib4f7f9417839acf491eac1828bbae7b067988e06
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/44015
Tested-by: Ben Clayton <bclayton@google.com>
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
diff --git a/tests/regres/deqp/deqp.go b/tests/regres/deqp/deqp.go
index 33573bf..5975b64 100644
--- a/tests/regres/deqp/deqp.go
+++ b/tests/regres/deqp/deqp.go
@@ -293,7 +293,11 @@
 			env = cov.AppendRuntimeEnv(env, coverageFile)
 		}
 	}
-	logPath := filepath.Join(c.TempDir, fmt.Sprintf("%v.log", goroutineIndex))
+
+	logPath := "/dev/null" // TODO(bclayton): Try "nul" on windows.
+	if !util.IsFile(logPath) {
+		logPath = filepath.Join(c.TempDir, fmt.Sprintf("%v.log", goroutineIndex))
+	}
 
 nextTest:
 	for name := range tests {
@@ -316,7 +320,7 @@
 		}
 
 		var coverage *cov.Coverage
-		if c.CoverageEnv != nil && supportsCoverage { // IsFile() check here is for GLES tests that don't emit coverage.
+		if c.CoverageEnv != nil && supportsCoverage {
 			coverage, err = c.CoverageEnv.Import(coverageFile)
 			if err != nil {
 				log.Printf("Warning: Failed to process test coverage for test '%v'. %v", name, err)