Distinguish the intent of PackagingSpec

A PackagingSpec actually means either of two: an installation of a file
(i.e. putting the file on a filesystem image), or a simple gathering.
However, so far, the two different intents was not visible in
PackagingSpecs returns from TransitivePackagingSpecs().

With this change, the two different intents are recorded in
PackagingSpec. A PackagingSpec has a boolean field which records the
value of the SkipInstall() of the module where the PackagingSpec was
created from.

This could be used by a module like android_system_image which wants to
follow the "installation" semantic. For example, the module type doesn't
want to include a stub variant of a shared lib.

This change doesn't make use of the new field, yet.

Bug: 335506668
Test: go test ./...
Change-Id: If0106642a11ba804630df79b4c5ebd608a77a6b1
diff --git a/android/module_context.go b/android/module_context.go
index d3e2770..dea22ba 100644
--- a/android/module_context.go
+++ b/android/module_context.go
@@ -476,6 +476,7 @@
 		executable:            executable,
 		effectiveLicenseFiles: &licenseFiles,
 		partition:             fullInstallPath.partition,
+		skipInstall:           m.skipInstall(),
 	}
 	m.packagingSpecs = append(m.packagingSpecs, spec)
 	return spec
@@ -599,6 +600,7 @@
 		symlinkTarget:    relPath,
 		executable:       false,
 		partition:        fullInstallPath.partition,
+		skipInstall:      m.skipInstall(),
 	})
 
 	return fullInstallPath
@@ -640,6 +642,7 @@
 		symlinkTarget:    absPath,
 		executable:       false,
 		partition:        fullInstallPath.partition,
+		skipInstall:      m.skipInstall(),
 	})
 
 	return fullInstallPath