valgrind: support hyperscan warning

Issue on Ubuntu 19.04.

==18655== Conditional jump or move depends on uninitialised value(s)
==18655==    at 0x5454603: hs_alloc_scratch (in /usr/lib/x86_64-linux-gnu/libhs.so.5.1.0)
==18655==    by 0x3D5C9A: SCHSPreparePatterns (util-mpm-hs.c:707)
==18655==    by 0x215FEC: DetectMpmPrepareBuiltinMpms (detect-engine-mpm.c:364)
==18655==    by 0x20813A: SigGroupBuild (detect-engine-build.c:1932)
==18655==    by 0x21287B: SigLoadSignatures (detect-engine-loader.c:366)
==18655==    by 0x35A702: LoadSignatures (suricata.c:2419)
==18655==    by 0x35B0DD: PostConfLoadedDetectSetup (suricata.c:2574)
==18655==    by 0x35C827: main (suricata.c:2986)

https://github.com/intel/hyperscan/issues/148

qa/valgrind.suppress

@@ -79,4 +79,16 @@
    fun:*IfaceOffloadingLinux
    ...
 }
-
+{
+   Known warning, Hyperscan issue #149
+   Memcheck:Cond
+   fun:hs_alloc_scratch
+   fun:SCHSPreparePatterns
+   ...
+}
+{
+   Known warning, Hyperscan issue #149
+   Memcheck:Cond
+   fun:SCHSPreparePatterns
+   ...
+}