Handle target.bionic in bp2build.

Soong supports some hand-crafted target.<type> that match multiple os or
arch types to simplify configuring for similar targets. target.bionic is
used to match on both android and linux_bionic OSes for cases where they
should be handled the same way.

Test: build/bazel/ci/bp2build.sh
Change-Id: I47b6aaf3279e4d242c4fd0e12f24117eb98e0665

android/arch.go

@@ -1987,6 +1987,10 @@ func (m *ModuleBase) GetArchVariantProperties(ctx ArchVariantContext, propertySe
 	axisToProps[bazel.OsConfigurationAxis] = osToProp
 	axisToProps[bazel.OsArchConfigurationAxis] = archOsToProp
 
+	axisToProps[bazel.BionicConfigurationAxis] = map[string]interface{}{
+		"bionic": getTargetStruct(ctx, propertySet, archProperties, "Bionic"),
+	}
+
 	return axisToProps
 }