If you don't have pkg-config or libmirage < 1.2 installed, expect
standard compilation failure with some less or more readable output.
-By default, mirage2iso tries to use POSIX C extensions to get mmaped
-I/O. If your system isn't POSIX compliant, you might add '-DNO_POSIX'
-(or directly '-DNO_MMAPIO') to your CPPFLAGS.
+By default, mirage2iso uses GNU & POSIX C extensions. You can disable
+them by either defining NO_GNU or NO_POSIX (second implies first). You
+can disable only specific features too using following defines:
+ -DNO_GETOPT_LONG (GNU ext)
+ disable use of getopt_long()
+ -DNO_MMAPIO (POSIX ext)
+ disable use of ftruncate() and mmap() to get mmaped I/O