Soong: support Errorprone javacflags

Add support for an errorprone block in Java modules that accepts
additional javacflags for the errorprone build.

Sample:

    errorprone: {
        javacflags: ["-Xep:EqualsNaN:WARN"],
    },

Bug: 72004718
Test: m RUN_ERROR_PRONE=true
Test: manual - add block with ERROR to a project
Test: androidmk_test
Change-Id: I502248fe76c26aa19102f413af72a7324c35b7f4

java/java.go

@@ -142,6 +142,11 @@ type CompilerProperties struct {
 		Exclude_filter []string
 	}
 
+	Errorprone struct {
+		// List of javac flags that should only be used when running errorprone.
+		Javacflags []string
+	}
+
 	Proto struct {
 		// List of extra options that will be passed to the proto generator.
 		Output_params []string
@@ -646,6 +651,10 @@ func (j *Module) collectBuilderFlags(ctx android.ModuleContext, deps deps) javaB
 		flags.javacFlags = "$javacFlags"
 	}
 
+	if len(j.properties.Errorprone.Javacflags) > 0 {
+		flags.errorProneExtraJavacFlags = strings.Join(j.properties.Errorprone.Javacflags, " ")
+	}
+
 	// javaVersion flag.
 	sdk := sdkStringToNumber(ctx, String(j.deviceProperties.Sdk_version))
 	if j.properties.Java_version != nil {