removing relative zstd_local

Makefile

@@ -3,11 +3,14 @@
 # or uncomment the following line
 #zstd=1
 
+# to compile with local zstd headers
+# run `make zstd_local=<dir>`
+# zstd_local must be an absolute path
+
 CC		= cc
 AR		= ar
 SVB		= thirdparty/streamvbyte
 SVB16		= thirdparty/streamvbyte16
-SVB16TOSLOW5	= ../../
 SVBLIB		= $(SVB)/libstreamvbyte.a
 SVB16LIB	= $(SVB16)/libstreamvbyte16.a
 CPPFLAGS	+= -I include/ -I $(SVB)/include/ -I $(SVB16)
@@ -63,7 +66,7 @@ $(SVBLIB):
 	make -C $(SVB) no_simd=$(no_simd) libstreamvbyte.a
 
 $(SVB16LIB):
-	make -C $(SVB16) no_simd=$(no_simd) zstd=$(zstd) zstd_local=$(SVB16TOSLOW5)/$(zstd_local) libstreamvbyte16.a
+	make -C $(SVB16) no_simd=$(no_simd) zstd=$(zstd) zstd_local=$(zstd_local) libstreamvbyte16.a
 
 $(BUILD_DIR)/slow5.o: src/slow5.c src/slow5_extra.h src/slow5_idx.h src/slow5_misc.h src/klib/ksort.h $(SLOW5_H)
 	$(CC) $(CFLAGS) $(CPPFLAGS) $< -c -fpic -o $@