Silence miscellaneous 64-to-32-bit data loss warnings.

This resolves #341.
diff --git a/src/prof.c b/src/prof.c
index 93421ab..b387227 100644
--- a/src/prof.c
+++ b/src/prof.c
@@ -109,7 +109,7 @@
     1
 #endif
 ];
-static unsigned		prof_dump_buf_end;
+static size_t		prof_dump_buf_end;
 static int		prof_dump_fd;
 
 /* Do not dump any profiles until bootstrapping is complete. */