update readme, renice -20

Author: vanhauser-thc

GNUmakefile

@@ -96,7 +96,7 @@ ifneq "$(shell uname -m)" "x86_64"
 endif
 
 CFLAGS     ?= -O3 -funroll-loops $(CFLAGS_OPT)
-override CFLAGS += -Wall -g -Wno-pointer-sign -Wmissing-declarations\
+override CFLAGS += -Wall -g -Wno-pointer-sign -Wmissing-declarations -Wno-unused-result \
 			  -I include/ -DAFL_PATH=\"$(HELPER_PATH)\" \
 			  -DBIN_PATH=\"$(BIN_PATH)\" -DDOC_PATH=\"$(DOC_PATH)\"