LibC: Remove text relocation

Tweak the PLT trampoline to avoid generating textrels in LibC.
This allows us to share all the LibC mappings, reducing per-process
memory consumption by ~200 KB. :^)

Patch originally by @nico.

Userland/Libraries/LibELF/Arch/i386/plt_trampoline.S

@@ -45,7 +45,7 @@ _plt_trampoline:	# (obj, reloff)
 
 	pushl	20(%esp)		 # Copy of reloff
 	pushl	20(%esp)		 # Copy of obj
-	call	_fixup_plt_entry # Call the binder
+	call	_fixup_plt_entry@PLT # Call the binder
 	addl	$8,%esp			 # pop binder args
 	movl	%eax,20(%esp)	 # Store function to be called in obj