Predefined constants do not work, like _PI

[Sanqui]

_PI is defined with sym_AddEqu during sym_Init, but that's broken for some reason.

sanky@warata:~/romhacking/rgbds_$ cat test.asm
SECTION "rst00",HOME[0]

db _PI % 256
sanky@warata:~/romhacking/rgbds_$ rgbasm test.asm
ERROR:  test.asm(3) :
    '_PI' not defined
Segmentation fault (core dumped)

[Sanqui]

In addition, for purposes of comparison, constants like these are treated as undefined, but the opposite case still gets parsed. This is in contrast to real undefined constants, for which the opposite use case is not parsed.

Contrived example:

sanky@warata:~/romhacking/rgbds_$ cat test.asm
SECTION "rst00",HOME[0]
IF !DEF(WHATEVER)
    db "_WHATEVER IS NOT DEFINED\n"
ENDC

IF DEF(WHATEVER)
    stop
    db "_WHATEVER IS DEFINED\n"
ENDC
sanky@warata:~/romhacking/rgbds_$ ./rgbasm -o test_ test.asm
sanky@warata:~/romhacking/rgbds_$ cat test_
RGB2�������_WHATEVER IS NOT DEFINED



sanky@warata:~/romhacking/rgbds_$ gedit test.asm
sanky@warata:~/romhacking/rgbds_$ cat test.asm
SECTION "rst00",HOME[0]
IF !DEF(_Z80)
    db "_Z80 IS NOT DEFINED\n"
ENDC

IF DEF(_Z80)
    db "_Z80 IS DEFINED\n"
ENDC
sanky@warata:~/romhacking/rgbds_$ ./rgbasm -o test_ test.asm
sanky@warata:~/romhacking/rgbds_$ cat test_
RGB2�������_Z80 IS NOT DEFINED



sanky@warata:~/romhacking/rgbds_$ gedit test.asm
sanky@warata:~/romhacking/rgbds_$ cat test.asm
SECTION "rst00",HOME[0]
IF !DEF(_Z80)
    db "_Z80 IS NOT DEFINED\n"
ENDC

IF DEF(_Z80)
    stop
    db "_Z80 IS DEFINED\n"
ENDC
sanky@warata:~/romhacking/rgbds_$ ./rgbasm -o test_ test.asm
ERROR:  test.asm(7) :
    STOP is not a Z80 instruction
rgbasm: Assembly aborted in pass 1 (1 errors)!
sanky@warata:~/romhacking/rgbds_$