runtime: change int32 to intgo in findnull and findnullw

Update #6046.
This CL just does findnull and findnullw. There are other functions
to fix but doing them a few at a time will help isolate any (unlikely)
breakages these changes bring up in architectures I can't test
myself.

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/12520043

src/pkg/runtime/env_plan9.c

@@ -8,7 +8,8 @@
 byte*
 runtime·getenv(int8 *s)
 {
-	int32 fd, len, n, r;
+	int32 fd, n, r;
+	intgo len;
 	byte file[128];
 	byte *p;
 

src/pkg/runtime/env_posix.c

@@ -11,7 +11,8 @@ Slice syscall·envs;
 byte*
 runtime·getenv(int8 *s)
 {
-	int32 i, j, len;
+	int32 i, j;
+	intgo len;
 	byte *v, *bs;
 	String* envv;
 	int32 envc;

src/pkg/runtime/os_plan9.c

@@ -194,7 +194,8 @@ runtime·goexitsall(int8 *status)
 int32
 runtime·postnote(int32 pid, int8* msg)
 {
-	int32 fd, len;
+	int32 fd;
+	intgo len;
 	uint8 buf[128];
 	uint8 tmp[16];
 	uint8 *p, *q;

src/pkg/runtime/os_plan9_386.c

@@ -32,7 +32,7 @@ runtime·sighandler(void *v, int8 *s, G *gp)
 	Ureg *ureg;
 	uintptr *sp;
 	SigTab *sig, *nsig;
-	int32 len, i;
+	intgo len, i;
 
 	if(!s)
 		return NCONT;

src/pkg/runtime/os_plan9_amd64.c

@@ -40,7 +40,7 @@ runtime·sighandler(void *v, int8 *s, G *gp)
 	Ureg *ureg;
 	uintptr *sp;
 	SigTab *sig, *nsig;
-	int32 len, i;
+	intgo i, len;
 
 	if(!s)
 		return NCONT;

src/pkg/runtime/print.c

@@ -12,7 +12,7 @@ static void vprintf(int8*, byte*);
 // write to goroutine-local buffer if diverting output,
 // or else standard error.
 static void
-gwrite(void *v, int32 n)
+gwrite(void *v, intgo n)
 {
 	if(g == nil || g->writebuf == nil) {
 		runtime·write(2, v, n);

src/pkg/runtime/runtime.c

@@ -393,7 +393,7 @@ void
 runtime·parsedebugvars(void)
 {
 	byte *p;
-	int32 i, n;
+	intgo i, n;
 
 	p = runtime·getenv("GODEBUG");
 	if(p == nil)

src/pkg/runtime/runtime.h

@@ -717,8 +717,8 @@ extern	DebugVars	runtime·debug;
  */
 int32	runtime·strcmp(byte*, byte*);
 byte*	runtime·strstr(byte*, byte*);
-int32	runtime·findnull(byte*);
-int32	runtime·findnullw(uint16*);
+intgo	runtime·findnull(byte*);
+intgo	runtime·findnullw(uint16*);
 void	runtime·dump(byte*, int32);
 int32	runtime·runetochar(byte*, int32);
 int32	runtime·charntorune(int32*, uint8*, int32);

src/pkg/runtime/string.goc

@@ -10,10 +10,10 @@ package runtime
 
 String	runtime·emptystring;
 
-int32
+intgo
 runtime·findnull(byte *s)
 {
-	int32 l;
+	intgo l;
 
 	if(s == nil)
 		return 0;
@@ -22,10 +22,10 @@ runtime·findnull(byte *s)
 	return l;
 }
 
-int32
+intgo
 runtime·findnullw(uint16 *s)
 {
-	int32 l;
+	intgo l;
 
 	if(s == nil)
 		return 0;