Apply rtti settings to linux_bionic

Otherwise linking fails with:

ld.lld: error: undefined symbol: vtable for __cxxabiv1::__si_class_type_info
>>> referenced by contexts_split.cpp
>>>               contexts_split.o:(typeinfo for ContextsSplit) in archive out/soong/.intermediates/bionic/libc/libc_common/linux_bionic_x86_64_static/libc_common.a

ld.lld: error: undefined symbol: vtable for __cxxabiv1::__class_type_info
>>> referenced by contexts_split.cpp
>>>               contexts_split.o:(typeinfo for Contexts) in archive out/soong/.intermediates/bionic/libc/libc_common/linux_bionic_x86_64_static/libc_common.a

ld.lld: error: undefined symbol: vtable for __cxxabiv1::__si_class_type_info
>>> referenced by contexts_serialized.cpp
>>>               contexts_serialized.o:(typeinfo for ContextsSerialized) in archive out/soong/.intermediates/bionic/libc/libc_common/linux_bionic_x86_64_static/libc_common.a

ld.lld: error: undefined symbol: vtable for __cxxabiv1::__si_class_type_info
>>> referenced by system_properties.cpp
>>>               system_properties.o:(typeinfo for ContextsPreSplit) in archive out/soong/.intermediates/bionic/libc/libc_common/linux_bionic_x86_64_static/libc_common.a
clang-8: error: linker command failed with exit code 1 (use -v to see invocation)

Bug: 31559095
Test: prebuilts/build-tools/build-prebuilts.sh
Change-Id: I03a02c7e55948a0cd04bdcb5c090bb74e1723a0f
diff --git a/cc/compiler.go b/cc/compiler.go
index 90382f5..5ac5d79 100644
--- a/cc/compiler.go
+++ b/cc/compiler.go
@@ -391,7 +391,7 @@
 		flags.GlobalFlags = append([]string{"${config.ClangExternalCflags}"}, flags.GlobalFlags...)
 	}
 
-	if ctx.Device() {
+	if tc.Bionic() {
 		if Bool(compiler.Properties.Rtti) {
 			flags.CppFlags = append(flags.CppFlags, "-frtti")
 		} else {