rename "sp" to "spc", avoid conflict with 4510 opcodes

libsrc/runtime/pushax.s

@@ -5,7 +5,7 @@
 ;
 
         .export         push0, pusha0, pushax
-        .importzp       sp
+        .importzp       spc
 
         .macpack        cpu
 
@@ -20,21 +20,21 @@ pusha0: ldx     #0
 .proc   pushax
 
         pha                     ; (3)
-        lda     sp              ; (6)
+        lda     spc              ; (6)
         sec                     ; (8)
         sbc     #2              ; (10)
-        sta     sp              ; (13)
+        sta     spc              ; (13)
         bcs     @L1             ; (17)
-        dec     sp+1            ; (+5)
+        dec     spc+1            ; (+5)
 @L1:    ldy     #1              ; (19)
         txa                     ; (21)
-        sta     (sp),y          ; (27)
+        sta     (spc),y          ; (27)
         pla                     ; (31)
         dey                     ; (33)
 .if (.cpu .bitand ::CPU_ISET_65SC02)
-        sta     (sp)            ; (37)
+        sta     (spc)            ; (37)
 .else
-        sta     (sp),y          ; (38)
+        sta     (spc),y          ; (38)
 .endif
         rts                     ; (44/43)