Re-add math defines for MinGW
Re-add math defines for MinGW

Commit 5c79896 took away the math defines, these defines are needed under MinGW if strict ANSI compilation is performed
EvgeneOskin/oce,mathstuf/oce,tpaviot/oce,Tridify/oce,Tridify/oce,finetjul/oce,finetjul/oce,tpaviot/oce,EvgeneOskin/oce,EvgeneOskin/oce,EvgeneOskin/oce,BenoitPerrot/oce,Tridify/oce,heartvalve/oce,mathstuf/oce,EvgeneOskin/oce,Tech-XCorp/oce,finetjul/oce,BenoitPerrot/oce,mathstuf/oce,mathstuf/oce,Tridify/oce,BenoitPerrot/oce,heartvalve/oce,finetjul/oce,tpaviot/oce,Tech-XCorp/oce,heartvalve/oce,Tech-XCorp/oce,tpaviot/oce,heartvalve/oce,BenoitPerrot/oce,heartvalve/oce,Tech-XCorp/oce,Tech-XCorp/oce,Tridify/oce,tpaviot/oce,finetjul/oce,BenoitPerrot/oce,mathstuf/oce