tests: Migrate to newlib-nano and libgloss-htif

This deprecates the monolithic syscalls.c environment in favor of a more
structured board support package (BSP) based on newlib.

tests/Makefile

@@ -1,12 +1,18 @@
 GCC=riscv64-unknown-elf-gcc
 OBJDUMP=riscv64-unknown-elf-objdump
-CFLAGS=-mcmodel=medany -std=gnu99 -O2 -fno-common -fno-builtin-printf -Wall
-LDFLAGS=-static -nostdlib -nostartfiles -lgcc
+CFLAGS= -std=gnu99 -O2 -fno-common -fno-builtin-printf -Wall
+LDFLAGS= -static
+
+include libgloss.mk
 
 PROGRAMS = pwm blkdev accum charcount nic-loopback big-blkdev pingd
 
+.DEFAULT_GOAL := default
+
+.PHONY: default
 default: $(addsuffix .riscv,$(PROGRAMS))
 
+.PHONY: dumps
 dumps: $(addsuffix .dump,$(PROGRAMS))
 
 %.o: %.S
@@ -15,11 +21,14 @@ dumps: $(addsuffix .dump,$(PROGRAMS))
 %.o: %.c mmio.h
 	$(GCC) $(CFLAGS) -c $< -o $@
 
-%.riscv: %.o crt.o syscalls.o link.ld
-	$(GCC) -T link.ld $(LDFLAGS) $< crt.o syscalls.o -o $@
+%.riscv: %.o $(libgloss)
+	$(GCC) $(LDFLAGS) $< -o $@
 
 %.dump: %.riscv
 	$(OBJDUMP) -D $< > $@
 
+
+.PHONY: clean
 clean:
 	rm -f *.riscv *.o *.dump
+	$(if $(libgloss),rm -rf $(libgloss_builddir)/)