Fix class/struct mismatches in forward declarations.

This patch fixes some compiler warnings when compiling with clang.

BUG=none
TEST=Compile with clang and run unit tests.
Review URL: https://breakpad.appspot.com/368001

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@937 4c0a9323-5329-0410-9bdc-e9ce6186880e

src/google_breakpad/processor/minidump_processor.h

@@ -42,7 +42,7 @@ class Minidump;
 class ProcessState;
 class SourceLineResolverInterface;
 class SymbolSupplier;
-class SystemInfo;
+struct SystemInfo;
 // Return type for Process()
 enum ProcessResult {
   PROCESS_OK,                                 // The minidump was

src/google_breakpad/processor/source_line_resolver_interface.h

@@ -44,7 +44,7 @@ using std::string;
 
 struct StackFrame;
 struct WindowsFrameInfo;
-struct CFIFrameInfo;
+class CFIFrameInfo;
 
 class SourceLineResolverInterface {
  public:

src/google_breakpad/processor/stack_frame_cpu.h

@@ -47,7 +47,7 @@
 namespace google_breakpad {
 
 struct WindowsFrameInfo;
-struct CFIFrameInfo;
+class CFIFrameInfo;
 
 struct StackFrameX86 : public StackFrame {
   // ContextValidity has one entry for each relevant hardware pointer

src/google_breakpad/processor/stackwalker.h

@@ -54,7 +54,7 @@ class MinidumpContext;
 class SourceLineResolverInterface;
 struct StackFrame;
 class SymbolSupplier;
-class SystemInfo;
+struct SystemInfo;
 
 using std::set;
 

src/google_breakpad/processor/symbol_supplier.h

@@ -39,7 +39,7 @@ namespace google_breakpad {
 
 using std::string;
 class CodeModule;
-class SystemInfo;
+struct SystemInfo;
 
 class SymbolSupplier {
  public: