REORG: rename "pattern" files

They're now called "sample" everywhere to match their description.
diff --git a/Makefile b/Makefile
index c832338..8a96dd7 100644
--- a/Makefile
+++ b/Makefile
@@ -516,7 +516,7 @@
        src/lb_chash.o src/lb_fwlc.o src/lb_fwrr.o src/lb_map.o src/lb_fas.o \
        src/stream_interface.o src/dumpstats.o src/proto_tcp.o \
        src/session.o src/hdr_idx.o src/ev_select.o src/signal.o \
-       src/acl.o src/pattern.o src/memory.o src/freq_ctr.o src/auth.o
+       src/acl.o src/sample.o src/memory.o src/freq_ctr.o src/auth.o
 
 EBTREE_OBJS = $(EBTREE_DIR)/ebtree.o \
               $(EBTREE_DIR)/eb32tree.o $(EBTREE_DIR)/eb64tree.o \