Skip install rules for apexes with installable: false

When an apex sets installable: false call SkipInstall to prevent
creating the install rules, and don't report the install rules
to Make.

Fixes: 221261079
Test: m checkbuild
Change-Id: If94759b16f79ee10ddcf8ee89603ca9e822b74f5
diff --git a/apex/builder.go b/apex/builder.go
index 183c215..8c5f99b 100644
--- a/apex/builder.go
+++ b/apex/builder.go
@@ -856,6 +856,10 @@
 		installSuffix = imageCapexSuffix
 	}
 
+	if !a.installable() {
+		a.SkipInstall()
+	}
+
 	// Install to $OUT/soong/{target,host}/.../apex.
 	a.installedFile = ctx.InstallFile(a.installDir, a.Name()+installSuffix, a.outputFile,
 		a.compatSymlinks.Paths()...)