Support prebuilt shared libs end with versions

This commit changes how `cc/androidmk.go` generates LOCAL_MODULE_STEM,
LOCAL_MODULE_SUFFIX, and LOCAL_BUILT_MODULE_STEM.  Now, `splitFileExt()`
takes a file name and a list of expected file extensions.
`splitFileExt()` searches the first occurrence of expected file
extensions in the file name.  If it can not find any, it will simply
return the last file extension.

Before this commit, `cc/androidmk.go` simply extracts the last file
extension (e.g. `.so`).  However, if the prebuilt shared libs end with
version numbers (e.g. `libc++.so.1`), it will use `$(LOCAL_MODULE).1` as
LOCAL_BUILT_MODULE_STEM and this will lead to missing target ninja
error.

Bug: 111579848
Test: Build a program that links libc++_host (from prebuilts/clang)
Change-Id: Id96726c69705d518ea725bb6abd8ff4527ca0cbc
diff --git a/cc/androidmk.go b/cc/androidmk.go
index 228b64a..c510d98 100644
--- a/cc/androidmk.go
+++ b/cc/androidmk.go
@@ -192,7 +192,9 @@
 			}
 		}
 
-		fmt.Fprintln(w, "LOCAL_BUILT_MODULE_STEM := $(LOCAL_MODULE)"+outputFile.Ext())
+		_, _, ext := splitFileExt(outputFile.Base())
+
+		fmt.Fprintln(w, "LOCAL_BUILT_MODULE_STEM := $(LOCAL_MODULE)"+ext)
 
 		fmt.Fprintln(w, "LOCAL_SYSTEM_SHARED_LIBRARIES :=")
 
@@ -286,7 +288,8 @@
 func (library *toolchainLibraryDecorator) AndroidMk(ctx AndroidMkContext, ret *android.AndroidMkData) {
 	ret.Class = "STATIC_LIBRARIES"
 	ret.Extra = append(ret.Extra, func(w io.Writer, outputFile android.Path) {
-		fmt.Fprintln(w, "LOCAL_MODULE_SUFFIX := "+outputFile.Ext())
+		_, suffix, _ := splitFileExt(outputFile.Base())
+		fmt.Fprintln(w, "LOCAL_MODULE_SUFFIX := "+suffix)
 		fmt.Fprintln(w, "LOCAL_SYSTEM_SHARED_LIBRARIES :=")
 	})
 }
@@ -327,8 +330,8 @@
 	ret.Extra = append(ret.Extra, func(w io.Writer, outputFile android.Path) {
 		path := installer.path.RelPathString()
 		dir, file := filepath.Split(path)
-		stem := strings.TrimSuffix(file, filepath.Ext(file))
-		fmt.Fprintln(w, "LOCAL_MODULE_SUFFIX := "+filepath.Ext(file))
+		stem, suffix, _ := splitFileExt(file)
+		fmt.Fprintln(w, "LOCAL_MODULE_SUFFIX := "+suffix)
 		fmt.Fprintln(w, "LOCAL_MODULE_PATH := $(OUT_DIR)/"+filepath.Clean(dir))
 		fmt.Fprintln(w, "LOCAL_MODULE_STEM := "+stem)
 	})
@@ -340,9 +343,9 @@
 
 	ret.Extra = append(ret.Extra, func(w io.Writer, outputFile android.Path) {
 		path, file := filepath.Split(c.installPath.String())
-		stem := strings.TrimSuffix(file, filepath.Ext(file))
+		stem, suffix, _ := splitFileExt(file)
 		fmt.Fprintln(w, "LOCAL_SYSTEM_SHARED_LIBRARIES :=")
-		fmt.Fprintln(w, "LOCAL_MODULE_SUFFIX := "+outputFile.Ext())
+		fmt.Fprintln(w, "LOCAL_MODULE_SUFFIX := "+suffix)
 		fmt.Fprintln(w, "LOCAL_MODULE_PATH := "+path)
 		fmt.Fprintln(w, "LOCAL_MODULE_STEM := "+stem)
 		fmt.Fprintln(w, "LOCAL_NO_NOTICE_FILE := true")
@@ -360,8 +363,9 @@
 
 	ret.Extra = append(ret.Extra, func(w io.Writer, outputFile android.Path) {
 		c.libraryDecorator.androidMkWriteExportedFlags(w)
+		_, _, ext := splitFileExt(outputFile.Base())
 
-		fmt.Fprintln(w, "LOCAL_BUILT_MODULE_STEM := $(LOCAL_MODULE)"+outputFile.Ext())
+		fmt.Fprintln(w, "LOCAL_BUILT_MODULE_STEM := $(LOCAL_MODULE)"+ext)
 		fmt.Fprintln(w, "LOCAL_STRIP_MODULE := false")
 		fmt.Fprintln(w, "LOCAL_SYSTEM_SHARED_LIBRARIES :=")
 		fmt.Fprintln(w, "LOCAL_UNINSTALLABLE_MODULE := true")
@@ -380,12 +384,12 @@
 
 		path := c.path.RelPathString()
 		dir, file := filepath.Split(path)
-		stem := strings.TrimSuffix(file, filepath.Ext(file))
+		stem, suffix, ext := splitFileExt(file)
 		fmt.Fprintln(w, "LOCAL_STRIP_MODULE := false")
 		fmt.Fprintln(w, "LOCAL_SYSTEM_SHARED_LIBRARIES :=")
 		fmt.Fprintln(w, "LOCAL_USE_VNDK := true")
-		fmt.Fprintln(w, "LOCAL_BUILT_MODULE_STEM := $(LOCAL_MODULE)"+outputFile.Ext())
-		fmt.Fprintln(w, "LOCAL_MODULE_SUFFIX := "+filepath.Ext(file))
+		fmt.Fprintln(w, "LOCAL_BUILT_MODULE_STEM := $(LOCAL_MODULE)"+ext)
+		fmt.Fprintln(w, "LOCAL_MODULE_SUFFIX := "+suffix)
 		fmt.Fprintln(w, "LOCAL_MODULE_PATH := $(OUT_DIR)/"+filepath.Clean(dir))
 		fmt.Fprintln(w, "LOCAL_MODULE_STEM := "+stem)
 	})
@@ -408,8 +412,9 @@
 
 	ret.Extra = append(ret.Extra, func(w io.Writer, outputFile android.Path) {
 		c.libraryDecorator.androidMkWriteExportedFlags(w)
+		_, _, ext := splitFileExt(outputFile.Base())
 
-		fmt.Fprintln(w, "LOCAL_BUILT_MODULE_STEM := $(LOCAL_MODULE)"+outputFile.Ext())
+		fmt.Fprintln(w, "LOCAL_BUILT_MODULE_STEM := $(LOCAL_MODULE)"+ext)
 		fmt.Fprintln(w, "LOCAL_STRIP_MODULE := false")
 		fmt.Fprintln(w, "LOCAL_SYSTEM_SHARED_LIBRARIES :=")
 		fmt.Fprintln(w, "LOCAL_UNINSTALLABLE_MODULE := true")