bp2build: support strip properties.

This CL adds support to bp2build for generating all strip-related
properties into a strip dictionary as a parameter in the cc_library
macro.

With the dictionary, it's easy to organize related attributes and
directly expand into a stripped_shared_library's attributes.

Test: //build/bazel/tests/bionic:compare_libc_stripping
Test: TH
Fixes: b/187928597
Change-Id: Ifea68d48fe295e71a43b12876cb168c475a62187
diff --git a/cc/library.go b/cc/library.go
index 93bd56c..28605f5 100644
--- a/cc/library.go
+++ b/cc/library.go
@@ -259,6 +259,16 @@
 	Static_deps_for_static        bazel.LabelListAttribute
 	Dynamic_deps_for_static       bazel.LabelListAttribute
 	Whole_archive_deps_for_static bazel.LabelListAttribute
+
+	Strip stripAttributes
+}
+
+type stripAttributes struct {
+	Keep_symbols                 bazel.BoolAttribute
+	Keep_symbols_and_debug_frame bazel.BoolAttribute
+	Keep_symbols_list            bazel.StringListAttribute
+	All                          bazel.BoolAttribute
+	None                         bazel.BoolAttribute
 }
 
 type bazelCcLibrary struct {
@@ -323,6 +333,14 @@
 		Linkopts:            linkerAttrs.linkopts,
 		Use_libcrt:          linkerAttrs.useLibcrt,
 
+		Strip: stripAttributes{
+			Keep_symbols:                 linkerAttrs.stripKeepSymbols,
+			Keep_symbols_and_debug_frame: linkerAttrs.stripKeepSymbolsAndDebugFrame,
+			Keep_symbols_list:            linkerAttrs.stripKeepSymbolsList,
+			All:                          linkerAttrs.stripAll,
+			None:                         linkerAttrs.stripNone,
+		},
+
 		Shared_srcs:                   sharedAttrs.srcs,
 		Shared_srcs_c:                 sharedAttrs.srcs_c,
 		Shared_srcs_as:                sharedAttrs.srcs_as,