fix build (add -fcommon)

Author: heni

Makefile

@@ -12,7 +12,7 @@ ifeq ($m, 64)
 ARCH = -m64
 endif
 
-CFLAGS = $(ARCH) -O3 -std=gnu11 -Wall -mpclmul -march=core2 -mfpmath=sse -mssse3 -fno-strict-aliasing -fno-strict-overflow -fwrapv -DAES=1 -DCOMMIT=\"${COMMIT}\" -D_GNU_SOURCE=1 -D_FILE_OFFSET_BITS=64
+CFLAGS = $(ARCH) -O3 -std=gnu11 -Wall -fcommon -mpclmul -march=core2 -mfpmath=sse -mssse3 -fno-strict-aliasing -fno-strict-overflow -fwrapv -DAES=1 -DCOMMIT=\"${COMMIT}\" -D_GNU_SOURCE=1 -D_FILE_OFFSET_BITS=64
 LDFLAGS = $(ARCH) -ggdb -rdynamic -lm -lrt -lcrypto -lz -lpthread -lcrypto
 
 LIB = ${OBJ}/lib