[newlib-cygwin] Fix link when nosys.specs is used to link

[Corinna Vinschen]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=13665a7c30b13d872a5a7f9af4104b5edfa0e5cc

commit 13665a7c30b13d872a5a7f9af4104b5edfa0e5cc
Author: Tamar Christina <Tamar.Christina@arm.com>
Date:   Thu Jul 13 10:52:42 2017 +0000

    Fix link when nosys.specs is used to link
    
    This patch fixes the issue where nosys.specs is used to link.
    e.g. The use of crt0 without any support for semihosting requested.
    
    The AArch64 crt0 was missing an #ifdef for the initialise_monitor_handles
    which was causing the link to fail. Sorry for missing this before.

Diff:
---
 libgloss/aarch64/crt0.S | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/libgloss/aarch64/crt0.S b/libgloss/aarch64/crt0.S
index ed4dafc..cbff11a 100644
--- a/libgloss/aarch64/crt0.S
+++ b/libgloss/aarch64/crt0.S
@@ -144,8 +144,10 @@
 	sub	x2, x2, x0		/* Third arg: length of block */
 	bl	FUNCTION (memset)
 
+#ifdef ARM_RDI_MONITOR
 	/* Need to set up standard file handles */
 	bl	FUNCTION (initialise_monitor_handles)
+#endif
 
 	/* .init and .fini sections are used to create constructors
 	   and destructors.  Here we call the _init function and arrange