ffbuild: Add gzip -n flag to fix reproducible builds

Without this flag, timestamps were embedded into the final
binary if CUDA was enabled.

Signed-off-by: Rob Hall <robxnanocode@outlook.com>
Signed-off-by: Anton Khirnov <anton@khirnov.net>

ffbuild/common.mak

@@ -130,7 +130,7 @@ $(BIN2CEXE): ffbuild/bin2c_host.o
 ifdef CONFIG_PTX_COMPRESSION
 %.ptx.gz: TAG = GZIP
 %.ptx.gz: %.ptx
-	$(M)gzip -c9 $(patsubst $(SRC_PATH)/%,$(SRC_LINK)/%,$<) >$@
+	$(M)gzip -nc9 $(patsubst $(SRC_PATH)/%,$(SRC_LINK)/%,$<) >$@
 
 %.ptx.c: %.ptx.gz $(BIN2CEXE)
 	$(BIN2C) $(patsubst $(SRC_PATH)/%,$(SRC_LINK)/%,$<) $@ $(subst .,_,$(basename $(notdir $@)))