[analyzer] Do not attempt to get the pointee of void*

Do not attempt to get the pointee of void* while generating a bug report 
(otherwise it will trigger an assert inside RegionStoreManager::getBinding 
assert(!T->isVoidType() && "Attempting to dereference a void pointer!")).

Test plan: make check-all

Differential revision: https://reviews.llvm.org/D42396

llvm-svn: 323382
diff --git a/clang/test/Analysis/malloc.c b/clang/test/Analysis/malloc.c
index 6e3f3fa..50be4ef 100644
--- a/clang/test/Analysis/malloc.c
+++ b/clang/test/Analysis/malloc.c
@@ -1786,6 +1786,18 @@
   free(p);
 }
 
+void allocateSomeMemory(void *offendingParameter, void **ptr) {
+  *ptr = malloc(1);
+}
+
+void testNoCrashOnOffendingParameter() {
+  // "extern" is necessary to avoid unrelated warnings 
+  // on passing uninitialized value.
+  extern void *offendingParameter;
+  void* ptr;
+  allocateSomeMemory(offendingParameter, &ptr);
+} // expected-warning {{Potential leak of memory pointed to by 'ptr'}}
+
 // ----------------------------------------------------------------------------
 // False negatives.