Fixing a CMake dependency issue for the pcap bifs.

ninja said:

    ninja: warning: multiple rules generate
    scripts/base/bif/const.bif.bro. builds involving this target will
    not be correct; continuing anyway [-w dupbuild=warn]

Looks like there's a larger problem here involving *.bif of the same
name at different locations of the source tree. For now, I'ved fixed
this one by merging src/iosource/pcap/{const,functions}.bif into
pcap.bif.

testing/btest/Baseline/coverage.bare-load-baseline/canonified_loaded_scripts.log

@@ -3,7 +3,7 @@
 #empty_field	(empty)
 #unset_field	-
 #path	loaded_scripts
-#open	2016-07-12-17-20-37
+#open	2016-08-01-16-08-40
 #fields	name
 #types	string
 scripts/base/init-bare.bro
@@ -52,7 +52,7 @@ scripts/base/init-bare.bro
   build/scripts/base/bif/__load__.bro
     build/scripts/base/bif/stats.bif.bro
     build/scripts/base/bif/broxygen.bif.bro
-    build/scripts/base/bif/functions.bif.bro
+    build/scripts/base/bif/pcap.bif.bro
     build/scripts/base/bif/bloom-filter.bif.bro
     build/scripts/base/bif/cardinality-counter.bif.bro
     build/scripts/base/bif/top-k.bif.bro
@@ -135,4 +135,4 @@ scripts/base/init-bare.bro
     build/scripts/base/bif/plugins/Bro_SQLiteWriter.sqlite.bif.bro
 scripts/policy/misc/loaded-scripts.bro
   scripts/base/utils/paths.bro
-#close	2016-07-12-17-20-37
+#close	2016-08-01-16-08-40