Fix port-acorn32/15850: machdep.booted_kernel on acorn32 is incorrect.

This has been on my TODO list for some time and i found it time to fix it
since its pretty simple to do.

The patch checks if the kernel is booted from the `UnixFS' RISC OS filing
system (case unimportant) and if so interprets its name to get the unix
file name the kernel has. If it doesn't see this prefix it will asume its
just called `netbsd'

sys/arch/acorn32/stand/BtNetBSD/pling.BtNetBSD/BtNetBSD

@@ -1,5 +1,5 @@
 REM > BtNetBSD
-REM $NetBSD: BtNetBSD,v 1.3 2002/02/11 19:00:07 reinoud Exp $
+REM $NetBSD: BtNetBSD,v 1.4 2002/03/10 01:28:19 reinoud Exp $
 REM
 REM Copyright (c) 2000, 2001, 2002 Reinoud Zandijk
 REM Copyright (c) 1998, 1999, 2000 Ben Harris
@@ -78,6 +78,14 @@ REM get kernel name
 file$ = LEFT$(args$, INSTR(args$, " ")-1)
 PRINT"Booting ";file$;" ";args$''
 
+
+IF FNtolower(LEFT$(file$,9))="unixfs:$." THEN
+  kernelname$=MID$(file$, 10)
+ELSE
+  kernelname$="netbsd" : REM RISC OS file namen zeggen niets XXX
+ENDIF
+
+
 REM Get some space to mess with
 REM   Declare a large array ... and then wipe it/map it in in the OS_Mem loop
 REM   the difference is that RO4 won't map it in by default and
@@ -502,14 +510,14 @@ DEF PROCload_kernel_aout(file%)
  
   REM update new header structure
   new_hdr%!16 = symsize%
-  
+ 
   REM mark highest virtual address free in NetBSD's mapping
   vfreebase% = KERNEL_BASE + nbpp%*relocoff%
 
   REM `patch' symbol table stuff
   ssym% = 0
   esym% = 0
-  
+ 
   PROCfinish_relocationtable
 ENDPROC
 
@@ -671,7 +679,7 @@ DEF PROCnew_configuration_structure
     ; u_char machine_id[4]
         EQUD          machineId%
     ; char kernelname[80]
-        EQUS          LEFT$(file$+CHR$0+STRING$(80, " "), 80)
+        EQUS          LEFT$(kernelname$+CHR$0+STRING$(80, " "), 80)
     ; char args[512]
         EQUS          args$+CHR$0
         ]: P% += 512 - LEN(args$+CHR$0): [ OPT opt%
@@ -700,7 +708,7 @@ DEF PROCnew_configuration_structure
         EQUD 0
     ; u_int MDFsize
         EQUD 0
-    
+ 
     ; u_int display_phys
         EQUD          videomem_start%
     ; u_int display_start
@@ -715,10 +723,10 @@ DEF PROCnew_configuration_structure
         EQUD          FNvdu_var(9)    ; acorn32 port needs log(bitsperpixel)/log(2)
     ; u_int framerate
         EQUD          56 ; XXX why?
-    
+ 
     ; char reserved[512]
     ]: P% += 512: [ OPT opt%
-    
+ 
     ; u_int pagesize
         EQUD          nbpp%
     ; u_int drampages
@@ -810,7 +818,7 @@ DEF PROCold_configuration_structure
     ;vrampages%
         EQUD          totalvrampages%
     ;kernelname%
-        EQUS          LEFT$(file$+CHR$0+STRING$(80, " "), 80)
+        EQUS          LEFT$(kernelname$+CHR$0+STRING$(80, " "), 80)
     ;framerate%
         EQUD          56 ; XXXXX
     ;machine_id%
@@ -1070,7 +1078,7 @@ DEF PROCget_memory_configuration
     loop% += 64
     PROCtwirl
   ENDWHILE
-  
+ 
   IF emulateDRAMsize% > 0 THEN
     REM emulate HACK
     DRAM0% = DRAM_addr%(0)
@@ -1250,3 +1258,17 @@ DEF FNvdu_var(var%)
 
 DEF FNroundup(val%, size%)
 =val% + (size% - 1) AND NOT (size% - 1)
+
+
+DEF FNtolower(name$)
+  LOCAL A$, Ch$, i%
+  FOR i%=1 TO LEN(name$)
+    Ch$ = LEFT$(name$,1)
+    IF Ch$>="A" AND Ch$<="Z" THEN
+      A$ += CHR$(ASC(Ch$)+ASC("a")-ASC("A"))
+    ELSE
+      A$ += Ch$
+    ENDIF
+    name$ = MID$(name$, 2)
+  NEXT
+= A$