cleanup dynamic linker start code cruft

two actual issues: one is that __dynlink no longer wants/needs a GOT
pointer argument, so the code to generate that argument can be
removed. the other issue was that in the i386 code, argc/argv were
being loaded into registers that would be call-clobbered, then copied
to preserved registers, rather than just being loaded into the proper
call-preserved registers to begin with.

this cleanup is in preparation for adding new dynamic linker
functionality (ability to explicitly invoke the dynamic linker to run
a program).

src/ldso/arm/start.s

@@ -3,12 +3,9 @@
 _start:
 	ldr r0,[sp]
 	add r1,sp,#4
-	ldr r2,2f
+	bl __dynlink
-	add r2,pc,r2
-1:	bl __dynlink
 	mov r1,r0
 	mov r0,#0
 	tst r1,#1
 	moveq pc,r1
 	bx r1
-2:	.word _GLOBAL_OFFSET_TABLE_ - 1b - 4

src/ldso/i386/start.s

@@ -2,16 +2,13 @@
 .global _start
 _start:
 	xor %ebp,%ebp
-	pop %ecx
+	pop %edi
-	mov %esp,%eax
+	mov %esp,%esi
 	and $-16,%esp
-	mov %eax,%esi
-	mov %ecx,%edi
 	push %ebp
-	call 1f
+	push %ebp
-1:	addl $_GLOBAL_OFFSET_TABLE_,(%esp)
+	push %esi
-	push %eax
+	push %edi
-	push %ecx
 	call __dynlink
 	mov %esi,%esp
 	push %edi

src/ldso/x86_64/start.s

@@ -3,7 +3,6 @@
 _start:
 	mov (%rsp),%rdi
 	lea 8(%rsp),%rsi
-	lea _GLOBAL_OFFSET_TABLE_(%rip),%rdx
 	call __dynlink
 	xor %edx,%edx
 	jmp *%rax