[IA64] fix circular dependency on generation of asm-offsets.h

Fix?  One ugly hack is replaced by a different ugly hack.

Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/include/asm-ia64/ptrace.h b/include/asm-ia64/ptrace.h
index fc54492..a79d1a7 100644
--- a/include/asm-ia64/ptrace.h
+++ b/include/asm-ia64/ptrace.h
@@ -57,7 +57,9 @@
 #include <linux/config.h>
 
 #include <asm/fpu.h>
+#ifndef ASM_OFFSETS_C
 #include <asm/asm-offsets.h>
+#endif
 
 /*
  * Base-2 logarithm of number of pages to allocate per task structure