gc: delete old unsafe functions

Also update build to be able to run mkbuiltin again.
The export form has changed a little, so builtin.c has
more diffs than unsafe.go.

In CL 5650069, I just edited the documentation, a rarely
successful method of change.

R=ken2
CC=golang-dev
https://golang.org/cl/5662043

src/cmd/dist/build.c

@@ -1212,6 +1212,7 @@ cmdenv(int argc, char **argv)
 	xprintf(format, "GOBIN", gobin);
 	xprintf(format, "GOARCH", goarch);
 	xprintf(format, "GOOS", goos);
+	xprintf(format, "GOCHAR", gochar);
 	if(pflag) {
 		sep = ":";
 		if(streq(gohostos, "windows"))

src/cmd/gc/mkbuiltin

@@ -10,21 +10,22 @@
 
 set -e
 
-eval $(go tool make --no-print-directory -f ../../Make.inc go-env)
-if [ -z "$GC" ]; then
-	echo 'missing $GC - gomake failed?' 1>&2
+eval $(go tool dist env)
+if [ -z "$GOCHAR" ]; then
+	echo 'missing $GOCHAR - go tool dist failed?' 1>&2
 	exit 1
 fi
 
-go tool make mkbuiltin1
+GC=${GOCHAR}g
+gcc -o mkbuiltin1 mkbuiltin1.c
 rm -f _builtin.c
 for i in runtime unsafe
 do
 	go tool $GC -A $i.go
-	O=$O ./mkbuiltin1 $i >>_builtin.c
+	O=$GOCHAR ./mkbuiltin1 $i >>_builtin.c
 done
 
 # If _builtin.c has changed vs builtin.c.boot,
 # check in the new change.
 cmp -s _builtin.c builtin.c || cp _builtin.c builtin.c
-rm _builtin.c
+rm _builtin.c mkbuiltin1 unsafe.$GOCHAR runtime.$GOCHAR

src/cmd/gc/mkbuiltin1.c

@@ -6,13 +6,17 @@
 
 // Compile .go file, import data from .6 file, and generate C string version.
 
-#include <u.h>
-#include <libc.h>
 #include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+#include <stdarg.h>
 
 void esc(char*);
+void fatal(char*, ...);
 
-void
+int
 main(int argc, char **argv)
 {
 	char *name;
@@ -21,7 +25,7 @@ main(int argc, char **argv)
 
 	if(argc != 2) {
 		fprintf(stderr, "usage: mkbuiltin1 sys\n");
-		sysfatal("in file $1.6 s/PACKAGE/$1/\n");
+		fatal("in file $1.6 s/PACKAGE/$1/");
 	}
 
 	name = argv[1];
@@ -29,14 +33,14 @@ main(int argc, char **argv)
 
 	snprintf(buf, sizeof(buf), "%s.%s", name, getenv("O"));
 	if((fin = fopen(buf, "r")) == NULL) {
-		sysfatal("open %s: %r\n", buf);
+		fatal("open %s: %s", buf, strerror(errno));
 	}
 
 	// look for $$ that introduces imports
 	while(fgets(buf, sizeof buf, fin) != NULL)
 		if(strstr(buf, "$$"))
 			goto begin;
-	sysfatal("did not find beginning of imports\n");
+	fatal("did not find beginning of imports");
 
 begin:
 	printf("char *%simport =\n", name);
@@ -68,11 +72,11 @@ begin:
 		esc(p);
 		printf("\\n\"\n");
 	}
-	sysfatal("did not find end of imports\n");
+	fatal("did not find end of imports");
 
 end:
 	printf("\t\"$$\\n\";\n");
-	exits(0);
+	return 0;
 }
 
 void
@@ -84,3 +88,15 @@ esc(char *p)
 		putchar(*p);
 	}
 }
+
+void
+fatal(char *msg, ...)
+{
+	va_list arg;
+	
+	va_start(arg, msg);
+	fprintf(stderr, "fatal: ");
+	vfprintf(stderr, msg, arg);
+	fprintf(stderr, "\n");
+	exit(2);
+}

src/cmd/gc/unsafe.go

@@ -16,9 +16,3 @@ type Pointer uintptr // not really; filled in by compiler
 func Offsetof(any) uintptr
 func Sizeof(any) uintptr
 func Alignof(any) uintptr
-
-func Typeof(i interface{}) (typ interface{})
-func Reflect(i interface{}) (typ interface{}, addr Pointer)
-func Unreflect(typ interface{}, addr Pointer) (ret interface{})
-func New(typ interface{}) Pointer
-func NewArray(typ interface{}, n int) Pointer