only save and restore ebp when stack generation is turned on (for parameters taken or returned on the nsis stack), just like in the old working code

git-svn-id: https://svn.code.sf.net/p/nsis/code/NSIS/trunk@5789 212acab6-be3b-0410-9dea-997c60f758d6

Contrib/System/Source/Call.S

@@ -327,7 +327,6 @@ FUNC_DECL _CallProc
   push        ebx
   push        edi
   push        esi
-  push        ebp
 
   IFDEF SYSTEM_LOG_DEBUG
     SYSTEM_LOG_INIT
@@ -347,6 +346,7 @@ FUNC_DECL _CallProc
   jne         stack_expand_done
 
   ;# Save previous stack location
+  push        ebp
   mov         dword ptr [_LastStackReal],esp
   cmp         dword ptr [_LastStackPlace],0
   jne         stack_adjust
@@ -657,7 +657,6 @@ handling_error_option_done:
   ;# Return
   mov         eax,dword ptr [ebp+8]
   ;# Restore registers
-  pop         ebp
   pop         esi
   pop         edi
   pop         ebx