Cleanup Jamfile for minimax

[NAThompson]

No description provided.

[NAThompson]

Closes #1450

[ecorm]

When I try:

../../../../b2 -a

within the libs/math/tools/minimax directory, I get:

error: Unable to find file or target named
error:     '../config//has_mpfr'
error: referred to from project at
error:     '.'
error: could not resolve project reference '../config'

[NAThompson]

@ecorm : apologies-try once more!

[ecorm]

@NAThompson , it compiles for me now with your last change. Thanks!

./minimax
Running 1 test case...
info
Nothing to display
Variant              = 0
range                = [0,1]
Relative Error       = 1
Pin to Origin        = 0
Order (Num/Denom)    = 3/1
Target Precision     = 64
Working Precision    = 128
Skew                 = 0
Brake                = 50
X Offset             = 0
X scale              = 1
Y Offset             = 0

[ecorm]

@NAThompson , the Running 1 test case... output is a bit worrisome. The concern is that the Boost.Math test suite might try to run minimax and then get stuck because it's an interactive program. I don't know how the test suite is put together, sorry.