getpagesize(): remove "portability" claim.

This is just POSIX nonsense. Android, iOS/macOS, the BSDs, and glibc all have getpagesize(). Window doesn't, but Windows doesn't have sysconf(3) either, so there's not a strong "portability" argument to be had there!

Change-Id: Ieacfbb61c3612045f27c20c3fa4fa12694db2243
diff --git a/libc/bionic/getpagesize.cpp b/libc/bionic/getpagesize.cpp
index da97633..fbcabd8 100644
--- a/libc/bionic/getpagesize.cpp
+++ b/libc/bionic/getpagesize.cpp
@@ -29,7 +29,6 @@
 #include <unistd.h>
 #include "platform/bionic/page.h"
 
-// Portable code should use sysconf(_SC_PAGE_SIZE) directly instead.
 int getpagesize() {
   // We dont use sysconf(3) here because that drags in stdio, which makes static binaries fat.
   return page_size();