tetris compilation errors

tetris.c: In function ‘pdots’:
tetris.c:223: warning: incompatible implicit declaration of built-in function ‘abort’
tetris.c:275: warning: incompatible implicit declaration of built-in function ‘abort’
tetris.c: In function ‘draw’:
tetris.c:283: warning: incompatible implicit declaration of built-in function ‘abort’
tetris.c:292: warning: incompatible implicit declaration of built-in function ‘abort’
tetris.c: In function ‘move’:
tetris.c:300: warning: incompatible implicit declaration of built-in function ‘abort’
tetris.c:338: warning: incompatible implicit declaration of built-in function ‘abort’
tetris.c: In function ‘showtop’:
tetris.c:365: warning: incompatible implicit declaration of built-in function ‘abort’
tetris.c:367: warning: incompatible implicit declaration of built-in function ‘bzero’
tetris.c:395: warning: incompatible implicit declaration of built-in function ‘abort’
tetris.c: In function ‘savescore’:
tetris.c:406: warning: incompatible implicit declaration of built-in function ‘abort’
tetris.c:409: warning: incompatible implicit declaration of built-in function ‘bzero’
tetris.c:427: warning: incompatible implicit declaration of built-in function ‘strcpy’
tetris.c: In function ‘scarp’:
tetris.c:443: warning: incompatible implicit declaration of built-in function ‘abort’
tetris.c:458: warning: incompatible implicit declaration of built-in function ‘exit’
tetris.c:464: warning: incompatible implicit declaration of built-in function ‘abort’
tetris.c:505: warning: incompatible implicit declaration of built-in function ‘bcopy’
tetris.c:506: warning: incompatible implicit declaration of built-in function ‘bzero’
tetris.c:523: warning: incompatible implicit declaration of built-in function ‘abort’
tetris.c:537: warning: incompatible implicit declaration of built-in function ‘abort’
tetris.c: In function ‘nextclass’:
tetris.c:545: warning: incompatible implicit declaration of built-in function ‘abort’
tetris.c:556: warning: incompatible implicit declaration of built-in function ‘abort’
tetris.c: In function ‘main’:
tetris.c:605: error: storage size of ‘fds’ isn’t known
tetris.c:618: warning: incompatible implicit declaration of built-in function ‘strncpy’
tetris.c:619: warning: incompatible implicit declaration of built-in function ‘strcpy’
tetris.c:652: warning: incompatible implicit declaration of built-in function ‘exit’
tetris.c:751: warning: incompatible implicit declaration of built-in function ‘abort’
tetris.c:775: warning: incompatible implicit declaration of built-in function ‘bcopy’
tetris.c:820: warning: incompatible implicit declaration of built-in function ‘exit’
tetris.c:793: error: invalid lvalue in asm output 0