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/runtime/condes.s

@@ -23,7 +23,7 @@
 ; --------------------------------------------------------------------------
 ; Initialize library modules
 
-.segment        "INIT"
+.segment        "ONCE"
 
 .proc   initlib
 

libsrc/runtime/stkchk.s

@@ -28,7 +28,7 @@
 ; Initialization code. This is a constructor, so it is called on startup if
 ; the linker has detected references to this module.
 
-.segment        "INIT"
+.segment        "ONCE"
 
 .proc   initstkchk
 
@@ -101,7 +101,7 @@ Fail:   lda     #4
 ; ----------------------------------------------------------------------------
 ; Data
 
-.segment        "INITBSS"
+.segment        "INIT"
 
 ; Initial stack pointer value. Stack is reset to this in case of overflows to
 ; allow program exit processing.