Add check for executable stack/heap when rating Linux exploitability.

src/processor/exploitability_linux.h

Index: src/processor/exploitability_linux.h
===================================================================
--- src/processor/exploitability_linux.h	(revision 1487)
+++ src/processor/exploitability_linux.h	(working copy)
@@ -51,11 +51,11 @@
   virtual ExploitabilityRating CheckPlatformExploitability();
 
  private:
-  // This method takes the address of the instruction pointer and returns
+  // Takes the address of the instruction pointer and returns
   // whether the instruction pointer lies in a valid instruction region.
   bool InstructionPointerInCode(uint64_t instruction_ptr);
 
-  // This method checks the exception that triggered the creation of the
+  // Checks the exception that triggered the creation of the
   // minidump and reports whether the exception suggests no exploitability.
   bool BenignCrashTrigger(const MDRawExceptionStream *raw_exception_stream);
 
@@ -62,6 +62,10 @@
   // Checks if the stack pointer points to a memory mapping that is not
   // labelled as the stack.
   bool StackPointerOffStack(uint64_t stack_ptr);
+
+  // Checks if the stack or heap are marked executable according
+  // to the memory mappings.
+  bool ExecutableStackOrHeap();
 };
 
 }  // namespace google_breakpad