Set Jemalloc --disable-cache-oblivious to reduce memory overhead

Apparently for large size classes Jemalloc allocate some extra memory in
order to be CPU cache friendly, but the cost on memory usage is high
(can be up to 25% overhead for allocations of 16kb).
see jemalloc/jemalloc#1098 (comment)

p.s. from redis's perspective that looks like external fragmentation,
(i.e. allocated bytes will be low, and active pages bytes will be large)
which  can cause active-defrag to eat CPU cycles in vain.

deps/Makefile

@@ -106,7 +106,7 @@ endif
 
 jemalloc: .make-prerequisites
 	@printf '%b %b\n' $(MAKECOLOR)MAKE$(ENDCOLOR) $(BINCOLOR)$@$(ENDCOLOR)
-	cd jemalloc && ./configure --disable-cxx --with-version=5.3.0-0-g0 --with-lg-quantum=3 --with-jemalloc-prefix=je_ CFLAGS="$(JEMALLOC_CFLAGS)" LDFLAGS="$(JEMALLOC_LDFLAGS)" $(JEMALLOC_CONFIGURE_OPTS)
+	cd jemalloc && ./configure --disable-cxx --with-version=5.3.0-0-g0 --with-lg-quantum=3 --disable-cache-oblivious --with-jemalloc-prefix=je_ CFLAGS="$(JEMALLOC_CFLAGS)" LDFLAGS="$(JEMALLOC_LDFLAGS)" $(JEMALLOC_CONFIGURE_OPTS)
 	cd jemalloc && $(MAKE) lib/libjemalloc.a
 
 .PHONY: jemalloc