[boost] [context] Don't hard-code the assembler

Subject: [boost] [context] Don't hard-code the assembler
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2014-04-01 14:39:38

AMDG

This commit:
https://github.com/boostorg/context/commit/7534fe5d1c01e7f543d86607770e9c46aa799984

makes it impossible for me to run
b2 --with-context msvc-12.0
outside of the visual studio command prompt.
Please just use the assembler that the
toolset provides.

In Christ,
Steven Watanabe