Remove default_shared_libs

system_shared_libs has been modified to have the same behavior as
the newly added default_shared_libs, remove default_shared_libs in
favor of system_shared_libs.

This reverts Ia2349d84c70e503916f90a5d2702e135248f73df and renames
the default_shared_libs property in cc_object (which never had
system_shared_libs) to system_shared_libs.

Bug: 193559105
Test: m checkbuild
Change-Id: I46672e3a096b6ea94ff4c10e1c31e8fd010a163c
diff --git a/cc/linker.go b/cc/linker.go
index 14564b6..8c0476b 100644
--- a/cc/linker.go
+++ b/cc/linker.go
@@ -46,18 +46,11 @@
 	// list of module-specific flags that will be used for all link steps
 	Ldflags []string `android:"arch_variant"`
 
-	// list of system libraries that will be dynamically linked to shared library and executable
-	// modules that build against bionic (device or Linux bionic modules).  If unset, generally
-	// defaults to libc, libm, and libdl.  Set to [] to prevent linking against the defaults.
-	// Equivalent to default_shared_libs for modules that build against bionic, and ignored on
-	// modules that do not build against bionic.
+	// list of system libraries that will be dynamically linked to
+	// shared library and executable modules.  If unset, generally defaults to libc,
+	// libm, and libdl.  Set to [] to prevent linking against the defaults.
 	System_shared_libs []string `android:"arch_variant"`
 
-	// list of system libraries that will be dynamically linked to shared library and executable
-	// modules.  If unset, generally defaults to libc, libm, and libdl.  Set to [] to prevent
-	// linking against the defaults.  Equivalent to system_shared_libs, but applies to all modules.
-	Default_shared_libs []string `android:"arch_variant"`
-
 	// allow the module to contain undefined symbols.  By default,
 	// modules cannot contain undefined symbols that are not satisified by their immediate
 	// dependencies.  Set this flag to true to remove --no-undefined from the linker flags.
@@ -239,18 +232,6 @@
 	linker.Properties.Ldflags = append(linker.Properties.Ldflags, flags...)
 }
 
-// overrideDefaultSharedLibraries returns the contents of the default_shared_libs or
-// system_shared_libs properties, and records an error if both are set.
-func (linker *baseLinker) overrideDefaultSharedLibraries(ctx BaseModuleContext) []string {
-	if linker.Properties.System_shared_libs != nil && linker.Properties.Default_shared_libs != nil {
-		ctx.PropertyErrorf("system_shared_libs", "cannot be specified if default_shared_libs is also specified")
-	}
-	if linker.Properties.System_shared_libs != nil {
-		return linker.Properties.System_shared_libs
-	}
-	return linker.Properties.Default_shared_libs
-}
-
 // linkerInit initializes dynamic properties of the linker (such as runpath).
 func (linker *baseLinker) linkerInit(ctx BaseModuleContext) {
 	if ctx.toolchain().Is64Bit() {
@@ -351,13 +332,13 @@
 		deps.SharedLibs = append(deps.SharedLibs, linker.Properties.Target.Platform.Shared_libs...)
 	}
 
-	deps.SystemSharedLibs = linker.overrideDefaultSharedLibraries(ctx)
+	deps.SystemSharedLibs = linker.Properties.System_shared_libs
 	// In Bazel conversion mode, variations have not been specified, so SystemSharedLibs may
 	// inaccuarately appear unset, which can cause issues with circular dependencies.
 	if deps.SystemSharedLibs == nil && !ctx.BazelConversionMode() {
-		// Provide a default set of shared libraries if default_shared_libs and system_shared_libs
-		// are unspecified.  Note: If an empty list [] is specified, it implies that the module
-		// declines the default shared libraries.
+		// Provide a default system_shared_libs if it is unspecified. Note: If an
+		// empty list [] is specified, it implies that the module declines the
+		// default system_shared_libs.
 		deps.SystemSharedLibs = append(deps.SystemSharedLibs, ctx.toolchain().DefaultSharedLibraries()...)
 	}
 
@@ -593,11 +574,6 @@
 	} else {
 		specifiedDeps.systemSharedLibs = append(specifiedDeps.systemSharedLibs, linker.Properties.System_shared_libs...)
 	}
-	if specifiedDeps.defaultSharedLibs == nil {
-		specifiedDeps.defaultSharedLibs = linker.Properties.Default_shared_libs
-	} else {
-		specifiedDeps.defaultSharedLibs = append(specifiedDeps.defaultSharedLibs, linker.Properties.Default_shared_libs...)
-	}
 
 	return specifiedDeps
 }