Remove obsolete/driver.h and the associated functionality

The obsolete/driver.h header file has been obsolete
since R8B.

Remove that file, along with obsolete thread APIs for
drivers in the emulator and the test cases.

erts/emulator/Makefile.in

@@ -441,8 +441,6 @@ release_spec: all
 ifeq ($(ERLANG_OSTYPE), unix)
 	$(INSTALL_PROGRAM) $(BINDIR)/$(CS_EXECUTABLE) $(RELSYSDIR)/bin
 endif
-	$(INSTALL_DIR) $(RELEASE_PATH)/usr/include/obsolete
-	$(INSTALL_DATA) obsolete/driver.h $(RELEASE_PATH)/usr/include/obsolete
 endif
 endif
 
@@ -647,9 +645,6 @@ $(OBJDIR)/%.nkp.o: sys/common/%.c
 
 ifeq ($(GCC),yes)
 
-$(OBJDIR)/erl_obsolete.o: beam/erl_obsolete.c
-	$(CC) $(subst -Wstrict-prototypes, , $(subst -O2, $(GEN_OPT_FLGS), $(CFLAGS))) $(INCLUDES) -c $< -o $@
-
 $(OBJDIR)/erl_goodfit_alloc.o: beam/erl_goodfit_alloc.c
 	$(CC) $(subst -O2, $(GEN_OPT_FLGS) $(UNROLL_FLG), $(CFLAGS)) $(INCLUDES) -c $< -o $@
 endif
@@ -724,7 +719,7 @@ RUN_OBJS = \
 	$(OBJDIR)/erl_fun.o             $(OBJDIR)/erl_bif_port.o \
 	$(OBJDIR)/erl_term.o 		$(OBJDIR)/erl_node_tables.o \
 	$(OBJDIR)/erl_monitors.o	$(OBJDIR)/erl_process_dump.o \
-	$(OBJDIR)/erl_obsolete.o	$(OBJDIR)/erl_bif_timer.o \
+	$(OBJDIR)/erl_bif_timer.o \
 	$(OBJDIR)/erl_drv_thread.o      $(OBJDIR)/erl_bif_chksum.o \
 	$(OBJDIR)/erl_bif_re.o		$(OBJDIR)/erl_unicode.o \
 	$(OBJDIR)/packet_parser.o	$(OBJDIR)/safe_hash.o \