[Bf-committers] fix export File.cpp for VC++6

[Hiroshi Saito]

Hi there,

export_File.cpp has got a small problem with VC++6.
('M_1_PI'  in not defined in VC++6 .)

It requires;
#ifndef  M_1_PI
#define M_1_PI  0.318309886183790671538   
#endif

Cheers
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Hiroshi Saito