runtime, net: fixes from CL 68490043 review

These are mistakes in the first big NaCl CL.

LGTM=minux.ma, iant
R=golang-codereviews, minux.ma, iant
CC=golang-codereviews
https://golang.org/cl/69200043

src/pkg/runtime/arch_amd64.h

@@ -11,10 +11,6 @@ enum {
 #else
 	RuntimeGogoBytes = 64,
 #endif
-#ifdef GOOS_nacl
-	PhysPageSize = 65536,
-#else
 	PhysPageSize = 4096,
-#endif
 	PCQuantum = 1
 };

src/pkg/runtime/arch_amd64p32.h

@@ -6,11 +6,7 @@ enum {
 	thechar = '6',
 	BigEndian = 0,
 	CacheLineSize = 64,
-#ifdef GOOS_solaris
-	RuntimeGogoBytes = 80,
-#else
 	RuntimeGogoBytes = 64,
-#endif
 #ifdef GOOS_nacl
 	PhysPageSize = 65536,
 #else

src/pkg/runtime/runtime.h

@@ -795,6 +795,8 @@ int32	runtime·charntorune(int32*, uint8*, int32);
  * first output value. Almost all code should write such
  * functions in .goc files, where goc2c (part of cmd/dist)
  * can arrange the correct alignment for the target system.
+ * Goc2c also takes care of conveying to the garbage collector
+ * which parts of the argument list are inputs vs outputs.
  *
  * Therefore, do NOT use this macro if at all possible.
  */