sysutils/shim: introduce new ARCH support (i386)

Makefile
    bump PORTREVISION;
    USE_CSTD: gnu89 became gnu99 [0];

files/
    *: if ARCH=i386, replaces ARCH with ia32;
    elf_ia32_efi.lds: sync OUTPUT_FORMAT [1];
    MokManager.c: used UINT32 for MokNum.

Reported by: pkg-fallout
Approved by: araujo (mentor)
Differential Revision: https://reviews.freebsd.org/D18572

[0] shim.c:2176:3: error: this decimal constant is unsigned only in ISO C90
[1] patch-elf_x86_64_efi.lds always appended -freebsd as OUTPUT_FORMAT