Use $RISCV includes for tests

tests/Makefile

@@ -2,7 +2,8 @@
 # RISCV Toolchain
 #################################
 
-PREFIX = riscv64-unknown-elf-
+PREFIX_NO_MINUS = riscv64-unknown-elf
+PREFIX = $(PREFIX_NO_MINUS)-
 
 GCC = $(PREFIX)gcc
 CXX = $(PREFIX)g++
@@ -21,7 +22,7 @@ ARCH = rv64imafdc
 ABI = lp64d
 ARCHFLAGS = -march=$(ARCH) -mabi=$(ABI)
 
-CFLAGS  = -std=gnu99 -O2 -fno-common -fno-builtin-printf -Wall
+CFLAGS  = -std=gnu99 -O2 -fno-common -fno-builtin-printf -Wall -I$(RISCV)/$(PREFIX_NO_MINUS)/include
 CFLAGS += $(ARCHFLAGS)
 LDFLAGS = -static
 

tests/encoding.h

@@ -1 +0,0 @@
-../toolchains/riscv-tools/riscv-tests/env/encoding.h

tests/hello.c

@@ -1,5 +1,5 @@
 #include <stdio.h>
-#include "encoding.h"
+#include "riscv-pk/encoding.h"
 #include "marchid.h"
 
 int main(void) {

tests/mt-hello.c

@@ -1,4 +1,4 @@
-#include "encoding.h"
+#include "riscv-pk/encoding.h"
 #include <stdio.h>
 #include "marchid.h"