Fix format specifier in proc maps to support 32-bit architectures.

src/google_breakpad/processor/proc_maps_linux.h

Index: src/google_breakpad/processor/proc_maps_linux.h
===================================================================
--- src/google_breakpad/processor/proc_maps_linux.h	(revision 1481)
+++ src/google_breakpad/processor/proc_maps_linux.h	(working copy)
@@ -23,8 +23,8 @@
   };
 
   // The address range [start,end) of mapped memory.
-  uintptr_t start;
-  uintptr_t end;
+  uint64_t start;
+  uint64_t end;
 
   // Byte offset into |path| of the range mapped into memory.
   uint64_t offset;