Make Ada a first class citizen

Some remarks on the make process:
  o We usually leave Ada specs (.ads files which are like c headers)
    together with the bodies (implementations in .adb files) in one
    directory. So we have to know, where they live.
  o If there is no matching .adb an .ads is a valid source file and
    we'll generate an object file from it.
  o Object files need to have the same basename as their source files :-/
    That's why we put them in build/<class>/ dirs now.
  o We track dependencies by looking at the compiler output (.ali files
    which accompany every .o). This way we don't need any gnatmake
    magic, or even more complex, less portable tools.

For ADAFLAGS_common, I simply copied the CFLAGS_common whilst dropping
everything unsupported and adding sane warning options.

The set of language features is highly restricted (see gnat.adc). This
should suit the embedded nature of coreboot and helps proving absence
of runtime errors with SPARK.

Change-Id: I70df9adbd467ecd2dc7c5c1cf418b7765aca4e93
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/13044
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-by: Edward O'Callaghan <edward.ocallaghan@koparo.com>
4 files changed