Declare __page_shift and __page_size with C linkage.

__page_shift and __page_size were accidentally declared in unistd.h with
C linkage - their implementation needs to use the same linkage.

Going forward, though, let's stop the inlining madness and let's kill
the non-standard __getpageshift(). This patch takes getpagesize(3) out
of line and removes __getpageshift but fixes __page_shift and __page_size
for backwards binary compatibility.

Change-Id: I35ed66a08989ced1db422eb03e4d154a5d6b5bda
Signed-off-by: Bernhard Rosenkraenzer <Bernhard.Rosenkranzer@linaro.org>
diff --git a/libc/include/unistd.h b/libc/include/unistd.h
index 98970ae..61d3d6e 100644
--- a/libc/include/unistd.h
+++ b/libc/include/unistd.h
@@ -170,14 +170,7 @@
 
 extern int  acct(const char*  filepath);
 
-static __inline__ int getpagesize(void) {
-  extern unsigned int __page_size;
-  return __page_size;
-}
-static __inline__ int __getpageshift(void) {
-  extern unsigned int __page_shift;
-  return __page_shift;
-}
+int getpagesize(void);
 
 extern int sysconf(int  name);