64-bit processor can't handle 32-bit ppc minidumps due to struct padding

differences on 64- and 32-bit CPUs.  Force 32-bit alignment rules for
32-bit ppc context struct.  r=nealsid

http://groups.google.com/group/google-breakpad-dev/browse_thread/thread/21a8e99c4800b51d


git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@273 4c0a9323-5329-0410-9bdc-e9ce6186880e

src/google_breakpad/common/minidump_cpu_ppc.h

@@ -104,6 +104,11 @@ typedef struct {
 
 #define MD_CONTEXT_PPC_GPR_COUNT 32
 
+/* Use the same 32-bit alignment when accessing this structure from 64-bit code
+ * as is used natively in 32-bit code.  #pragma pack is a MSVC extension
+ * supported by gcc. */
+#pragma pack(push, 4)
+
 typedef struct {
   /* context_flags is not present in ppc_thread_state, but it aids
    * identification of MDRawContextPPC among other raw context types,
@@ -131,6 +136,8 @@ typedef struct {
   MDVectorSaveAreaPPC   vector_save;
 } MDRawContextPPC;  /* Based on ppc_thread_state */
 
+#pragma pack(pop)
+
 /* For (MDRawContextPPC).context_flags.  These values indicate the type of
  * context stored in the structure.  MD_CONTEXT_PPC is Breakpad-defined.  Its
  * value was chosen to avoid likely conflicts with MD_CONTEXT_* for other