Cleanup of redundant/useless header file inclusion.
ISC style lint, primarily for function declarations and standalone
comments -- ie, those that appear on a line without any code, which
should be written as follows:
/*
* This is a comment.
*/
included, we get conflicts between <string.h> and <linux/string.h> that
make the compilation fail. This change also eliminates compiler warnings when
os.c is compiled on a system with a 2.2 <linux/capability.h>.