rt: Remove unused saves from __morestack

Author: brson

src/rt/arch/i386/morestack.S

@@ -156,12 +156,6 @@ MORESTACK:
 	testl %eax,%eax
 	jz .L$bail
 
-	// Save the the correct %esp value for our grandparent frame,
-	// for the unwinder
-	// FIXME: This isn't used
-	leal 20(%ebp), %eax
-	movl %eax, -4(%ebp)
-
 	// The arguments to upcall_new_stack
 
 	// The size of the stack arguments to copy to the new stack,

src/rt/arch/x86_64/morestack.S

@@ -49,10 +49,7 @@ MORESTACK:
 	// Calculate the CFA as on offset from %ebp
 	.cfi_def_cfa_register %rbp
 
-	// Save the grandparent stack pointer for the unwinder
-	// FIXME: This isn't used
-	leaq 24(%rbp), %rax
-	pushq %rax
+	pushq $0 // Alignment
 
 	// FIXME: libgcc also saves rax. not sure if we need to