aarch64: fix start code for static pie

There are three flavors of the crt startup code:

1) crt1.o used for non-pie,
2) Scrt1.o used for dynamic linked pie (dynamic linker relocates),
3) rcrt1.o used for static linked pie (self relocation is needed)

In the --enable-static-pie case crt1.o is built with -DPIC and in case
of static linking it interposes _dl_relocate_static_pie in libc to
avoid self relocation.

Scrt1.o is built with -DPIC -DSHARED and it relies on GOT entries that
the static linker cannot relax and thus need relocation before the
start code is executed, so rcrt1.o needs separate implementation.

This implementation does not work for .text > 4G position independent
executables, which is fine since the toolchain does not support
-mcmodel=large with -fPIE.

Tests pass with ld/22269 and ld/22263 binutils bugs fixed.

	* sysdeps/aarch64/start.S (_start): Handle PIC && !SHARED case.

ChangeLog

@@ -1,3 +1,7 @@
+2017-12-18  Szabolcs Nagy  <szabolcs.nagy@arm.com>
+
+	* sysdeps/aarch64/start.S (_start): Handle PIC && !SHARED case.
+
 2017-12-16  Aurelien Jarno  <aurelien@aurel32.net>
 
 	[BZ #22505]

sysdeps/aarch64/start.S

@@ -60,7 +60,8 @@ _start:
 	/* Setup stack limit in argument register */
 	mov	x6, sp
 
-#ifdef SHARED
+#ifdef PIC
+# ifdef SHARED
         adrp    x0, :got:main
 	ldr     PTR_REG (0), [x0, #:got_lo12:main]
 
@@ -69,6 +70,14 @@ _start:
 
         adrp    x4, :got:__libc_csu_fini
 	ldr     PTR_REG (4), [x4, #:got_lo12:__libc_csu_fini]
+# else
+	adrp	x0, main
+	add	x0, x0, :lo12:main
+	adrp	x3, __libc_csu_init
+	add	x3, x3, :lo12:__libc_csu_init
+	adrp	x4, __libc_csu_fini
+	add	x4, x4, :lo12:__libc_csu_fini
+# endif
 #else
 	/* Set up the other arguments in registers */
 	MOVL (0, main)