PNaCl: Build a PPAPI shims library for all architectures

ppapi/native_client/src/untrusted/pnacl_irt_shim/shim_entry.c

Index: ppapi/native_client/src/untrusted/pnacl_irt_shim/shim_entry.c
diff --git a/ppapi/native_client/src/untrusted/pnacl_irt_shim/shim_entry.c b/ppapi/native_client/src/untrusted/pnacl_irt_shim/shim_entry.c
index e143c926129adf2ef5a83f4b01e277f302d83160..1d64ee79ce400c5ad4f03740aa0f84192d14dc68 100644
--- a/ppapi/native_client/src/untrusted/pnacl_irt_shim/shim_entry.c
+++ b/ppapi/native_client/src/untrusted/pnacl_irt_shim/shim_entry.c
@@ -16,6 +16,8 @@
  * See nacl_startup.h for the layout at the argument pointer.
  */
 void _pnacl_wrapper_start(uint32_t *info) {
+  /* The PNaCl PPAPI shims are only needed on x86-64. */
+#if defined(__x86_64__)
   Elf32_auxv_t *auxv = nacl_startup_auxv(info);
 
   Elf32_auxv_t *entry = NULL;
@@ -48,6 +50,7 @@ void _pnacl_wrapper_start(uint32_t *info) {
    * seems brittle (what if the bitcode link was separated from translation).
    * Thus we always wrap _start, even if there is no IRT auxv entry.
    */
+#endif
 
   /*
    * Call the user entry point function.  It should not return.