[GPU][AMD] Fix lldb hipcc tests to link using libstdc++ (#69)

This commit changes the test Makefile.rules to force linking with
libstdc++ when building with hipcc.

An upstream [change](llvm#164462)
modified the test link commands to add -nostdlib++ to avoid linking both the
internal llvm c++ library and the external system c++ standard library.
This was causing linking failures when building with hipcc because it
expects to use the system libstdc++ library.

Author: dmpots

lldb/packages/Python/lldbsuite/test/make/Makefile.rules

@@ -107,11 +107,13 @@ endif
 # Override CC and CXX when building a hip application.
 #
 # Use the same hipcc compiler for compiling and linking everything.
+# Make sure to link to the system standard library since hipcc needs it.
 #----------------------------------------------------------------------
 ifneq "$(strip $(HIP_SOURCES))" ""
 	override CC := $(HIPCC)
 	override CXX := $(HIPCC)
 	override CC_TYPE := hip
+	override USE_SYSTEM_STDLIB := 1
 endif
 
 #----------------------------------------------------------------------