Add InstallForceOS, fix testcases for host

Robolectric tests compile against device modules but are installed
and run as host modules.  Allow a module to override its install
OS.

Test: TestPathForModuleInstall
Change-Id: Icf37bb3d4cc1222a9b079602c6a5fdb8b51c86ed
diff --git a/android/module.go b/android/module.go
index 96c2e1e..2a2f5ad 100644
--- a/android/module.go
+++ b/android/module.go
@@ -172,6 +172,7 @@
 	InstallInRecovery() bool
 	InstallInRoot() bool
 	InstallBypassMake() bool
+	InstallForceOS() *OsType
 
 	RequiredModuleNames() []string
 	HostRequiredModuleNames() []string
@@ -213,6 +214,7 @@
 	InstallInRecovery() bool
 	InstallInRoot() bool
 	InstallBypassMake() bool
+	InstallForceOS() *OsType
 	SkipInstall()
 	ExportedToMake() bool
 	NoticeFile() OptionalPath
@@ -893,6 +895,10 @@
 	return false
 }
 
+func (m *ModuleBase) InstallForceOS() *OsType {
+	return nil
+}
+
 func (m *ModuleBase) Owner() string {
 	return String(m.commonProperties.Owner)
 }
@@ -1683,6 +1689,10 @@
 	return m.module.InstallBypassMake()
 }
 
+func (m *moduleContext) InstallForceOS() *OsType {
+	return m.module.InstallForceOS()
+}
+
 func (m *moduleContext) skipInstall(fullInstallPath InstallPath) bool {
 	if m.module.base().commonProperties.SkipInstall {
 		return true