Bump compiler plugins Clang baseline to 5.0.2

...as discussed at
<https://lists.freedesktop.org/archives/libreoffice/2018-November/081435.html>
"minutes of ESC call ..."

Change-Id: Ia053da171d59747984546f38e19da808825b4f79
Reviewed-on: https://gerrit.libreoffice.org/63832
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

compilerplugins/clang/constparams.cxx

@@ -216,7 +216,7 @@ bool ConstParams::CheckTraverseFunctionDecl(FunctionDecl * functionDecl)
 
     // calculate the ones we want to check
     bool foundInterestingParam = false;
-    for (const ParmVarDecl *pParmVarDecl : compat::parameters(*functionDecl)) {
+    for (const ParmVarDecl *pParmVarDecl : functionDecl->parameters()) {
         // ignore unused params
         if (pParmVarDecl->getName().empty()
             || pParmVarDecl->hasAttr<UnusedAttr>())