Update source to SDL2 2.0.12

Edward Rudd

2020-05-02 03f8528315fa46c95991a34f3325d7b33ae5538c

 source/src/libm/e_pow.c

@@ -63,6 +63,10 @@
#pragma warning ( disable : 4756 )
#endif

#ifdef __WATCOMC__ /* Watcom defines huge=__huge */
#undef huge
#endif

static const double
bp[] = {1.0, 1.5,},
dp_h[] = { 0.0, 5.84962487220764160156e-01,}, /* 0x3FE2B803, 0x40000000 */