Add a C-compiler about z80-playground-cpm-fat

[skx]

Currently preferring AzTec's C compiler:

• Fewer files.
• Seems to work under emulation.
• Have built working code with it.

We'll see if it's as good on real hardware, and then choose.

Links:

• https://hackaday.io/project/173479-my-cpm-version-1a/log/181039-adding-a-native-c-compiler
• https://www.aztecmuseum.ca/compilers.htm#cpm

Sample code:

/* WRITE.c - Steve Kemp 2021
 *
 * Write some text to the specified file, arguments are space-separated,
 * with a trailing newline.
 *
 * Usage:
 *
 *    WRITE TEST.TXT This is a test
 *
 * Compilation:
 *
 *    CC WRITE
 *    AS WRITE
 *    LN WRITE.O T.LIB C.LIB
 *
 */

#include <stdio.h>


FILE *fp=NULL;
FILE *fp2=NULL;

#define TRUE 1
#define FALSE 0

main(argc, argv)
int argc;
char *argv[];
{
    int i = 0;
    FILE *fp=NULL;

    /* need at least prog + file + one argument */
    if ( argc < 3 ) {
        printf("Usage: %s path.ext text to write ..\n");
        exit(1);
    }

    /* open output file */
    fp = fopen( argv[1] );
    if ( fp == NULL )  {
        printf("Failed to open file for writing.\n");
        exit(1);
    }

    /* write each argument out */
    for( i = 2; i < argc; i++ ){
        fprintf(fp, "%s%s", argv[i], (i+1 < argc) ? " " : "\n" );
    }

    /* All done */
    fclose(fp);
    exit(0);
}