ARC: Enable shared crt1

Currently crt1 takes address of functions (main,_init,_fini) directly
which doesn't generate truely position independent code, but zero based
values instead. e.g.

|  __start:
|        ...
|	add_s   r2,sp,0x4
| 	mov_s	r0, main

generates to

|  000156ec <__start>:
|  ...
|     156f4:	add_s	r2,sp,0x4
|     156f6:	mov_s	r0,0x15f7c
|  ...
|  00015f7c <main>:
|     15f7c:	push_s	blink

This works just fine for the normal (non PIE) dynamic executables since
they are loaded at address 0. However this is not true for PIE
executables. So for Scrt1 we use a true position independent way when
taking function addresses.

Cc: uclibc@uclibc.org <uclibc@uclibc.org>
Cc: devel@uclibc-ng.org <devel@uclibc-ng.org>
Cc: Cupertino Miranda <cmiranda@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

libc/sysdeps/linux/arc/crt1.S

@@ -41,11 +41,15 @@ __start:
 
 	mov_s	r5, r0		; rltd_fini
 	add_s	r2, sp, 4	; argv
-
+#ifdef L_Scrt1
+	add	r0, pcl, @main@pcl
+	add	r3, pcl, @_init@pcl
+	add	r4, pcl, @_fini@pcl
+#else
 	mov_s	r0, main
 	mov_s	r3, _init
 	mov	r4, _fini
-
+#endif
 	and	sp, sp, -8
 	mov	r6, sp