Needs review.

--HG--
branch : pubkey-options
extra : convert_revision : 26872f944d79ddacff1070aab32115a6d726392c

--HG--
branch : libtommath-dropbear
extra : convert_revision : 2af95f00ebd5bb7a28b3817db1218442c935388e

Use $CC rather than $LD for linking

--HG--
extra : convert_revision : 31dcd7a22983ef19d6c63248e415e71d292dd0ec

--HG--
extra : convert_revision : 138a11bc1e2babcd8b1182e6cb2a85d4e9404b11

* bn_mp_clear.c is changed so that some vars are volatile,
so that the compiler won't optimise away

--HG--
branch : libtommath-dropbear
extra : convert_revision : 6c790cad5a7fa866ad062cb3a0c279f7ba788583

From ltm-0.35.tar.bz2 SHA1 of 3f193dbae9351e92d02530994fa18236f7fde01c

--HG--
branch : libtommath-orig
extra : convert_revision : 2b4b13ac88b2a81e5c86ba868c92c6a452630e02

--HG--
branch : libtomcrypt-dropbear
extra : convert_revision : 20dccfc09627970a312d77fb41dc2970b62689c3

From crypt-1.05.tar.bz2, SHA1 of 88250202bb51570dc64f7e8f1c943cda9479258f

--HG--
branch : libtomcrypt-orig
extra : convert_revision : 5c0c50e93111636ccf8deb758a689ad713797baf