GCC Spec file for ARMv8/Aarch64?

[Jeffrey Walton]

I have a LeMaker HiKey dev board
(http://www.lemaker.org/product-hikey-index.html). Its ARMv8/Aarch64
with an 8-core A-53 processor.

The problem I have is each time I SSH into the device I usually need
to do the following to get the Crypto extensions that are available
natively (GCC fails to consume `-march=native`):

    export CXXFLAGS="-DNDEBUG -g3 -O3 -march=armv8-a+crypto -mcpu=cortex-a53"

I have to do similar when testing CRC32 extensions, and often need to
`-march=armv8-a+crc` or `-march=armv8-a+crc+crypto`.

I'd like to add `-march=armv8-a+crc+crypto -mcpu=cortex-a53` to a GCC
spec file so its always available for various programs, without the
need for source'ing .bash_profile. However, I don't see a GCC spec
file that seems to cover it:

    $ find /usr/lib -name '*.spec*'
    /usr/lib/gcc/aarch64-linux-gnu/4.9/libgomp.spec
    /usr/lib/gcc/aarch64-linux-gnu/4.9/libitm.spec

I also know GCC is using something, but it does not tell me what it is:

   $ gcc -v
   Using built-in specs.
   ...

My questions are:

    * What is the name of the built-in GCC spec file?
    * What is the formula to add the options if they are not specified
on the command line?

I visited http://gcc.gnu.org/onlinedocs/gcc/Spec-Files.html, but I
don't see an answer to the first question. The answer to the second
question is probably in the man page, but I have to admit I'm not
really versed with the Spec file grammar.

Jeff