Add the ability to GCC_NEED_DECLARATION{S} for looking in arbitrary

Add the ability to GCC_NEED_DECLARATION{S} for looking in arbitrary
header files when searching for function declarations.  Use this
functionality to check for getrlimit/setrlimit.
        * aclocal.m4 (GCC_NEED_DECLARATION): Accept an optional second
        argument, which is typically preprocessor code used to draw in
        additional header files when looking for a function declaration.
        (GCC_NEED_DECLARATIONS): Likewise.
        * configure.in (GCC_NEED_DECLARATIONS): Add checks for getrlimit
        and setrlimit, search for them in sys/resource.h.
        * acconfig.h: Add stubs for NEED_DECLARATION_GETRLIMIT and
        NEED_DECLARATION_SETRLIMIT.
        * system.h: Prototype getrlimit/setrlimit if necessary.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@20831 138bc75d-0d04-0410-961f-82ee72b054a4