Remove redundant "unknown option" error messages (#1441)

`getopt` already prints "unrecognized option"

src/asm/main.cpp

@@ -281,7 +281,6 @@ int main(int argc, char *argv[]) {
 
 		// Unrecognized options
 		default:
-			fprintf(stderr, "FATAL: unknown option '%c'\n", ch);
 			printUsage();
 			exit(1);
 		}

src/fix/main.cpp

@@ -1372,7 +1372,6 @@ int main(int argc, char *argv[]) {
 			break;
 
 		default:
-			fprintf(stderr, "FATAL: unknown option '%c'\n", ch);
 			printUsage();
 			exit(1);
 		}

src/gfx/main.cpp

@@ -588,7 +588,6 @@ static char *parseArgv(int argc, char *argv[]) {
 			}
 			break;
 		default:
-			fprintf(stderr, "FATAL: unknown option '%c'\n", ch);
 			printUsage();
 			exit(1);
 		}

src/link/main.cpp

@@ -412,7 +412,6 @@ int main(int argc, char *argv[]) {
 			is32kMode = true;
 			break;
 		default:
-			fprintf(stderr, "FATAL: unknown option '%c'\n", ch);
 			printUsage();
 			exit(1);
 		}