getpagesize - get system page size
Return the number of bytes in a page. This is the system's
page size, which is not necessarily the same as the hardware
getpagesize is implemented as a library function in DLL
4.4.1. Depending on what is defined when the library is
compiled, this function returns EXEC_PAGESIZE (set to 4096
in Linux 0.99.11), NBPG (set to 4096 in Linux 0.99.11), or
NBPC (not defined in Linux 0.99.11 or DLL 4.4.1 libraries).
SVr4, 4.4BSD (this call first appeared in 4.2BSD).