Renamed INITBSS to INIT and INIT to ONCE.

The way we want to use the INITBSS segment - and especially the fact that it won't have the type bss on all ROM based targets - means that the name INITBSS is misleading. After all INIT is the best name from my perspective as it serves several purposes and therefore needs a rather generic name.

Unfortunately this means that the current INIT segment needs to be renamed too. Looking for a short (ideally 4 letter) name I came up with ONCE as it contains all code (and data) accessed only once during initialization.

libsrc/pce/clock.s

@@ -23,7 +23,7 @@
 
 .endproc
 
-        .segment        "INIT"
+        .segment        "ONCE"
 initclock:
         lda     #0
         ldx     #3

libsrc/pce/conio.s

@@ -10,7 +10,7 @@
 
         .macpack        longbranch
 
-        .segment        "INIT"
+        .segment        "ONCE"
 initconio:
         jsr     vce_init
         jsr     psg_init

libsrc/pce/irq.s

@@ -10,7 +10,7 @@
         .include        "extzp.inc"
 
 ; ------------------------------------------------------------------------
-.segment        "INIT"
+.segment        "ONCE"
 
 ; a constructor
 ;

libsrc/pce/psg.s

@@ -2,7 +2,7 @@
 
         .export         psg_init
 
-        .segment        "INIT"
+        .segment        "ONCE"
 psg_init:
         clx
         stz     PSG_GLOBAL_PAN          ; Clear global balance

libsrc/pce/vce.s

@@ -2,7 +2,7 @@
 
         .export         vce_init
 
-        .segment        "INIT"
+        .segment        "ONCE"
 vce_init:
         ; Set CTA to zero
         stz     VCE_ADDR_LO