Adding cython v0.20.2 in third-party.

third_party/cython/src/Cython/Includes/libc/math.pxd

Index: third_party/cython/src/Cython/Includes/libc/math.pxd
diff --git a/third_party/cython/src/Cython/Includes/libc/math.pxd b/third_party/cython/src/Cython/Includes/libc/math.pxd
new file mode 100644
index 0000000000000000000000000000000000000000..5711cd35823529584682b1ec0a8cb98cf409a7cd
--- /dev/null
+++ b/third_party/cython/src/Cython/Includes/libc/math.pxd
@@ -0,0 +1,102 @@
+cdef extern from "math.h" nogil:
+    double M_E
+    double M_LOG2E
+    double M_LOG10E
+    double M_LN2
+    double M_LN10
+    double M_PI
+    double M_PI_2
+    double M_PI_4
+    double M_1_PI
+    double M_2_PI
+    double M_2_SQRTPI
+    double M_SQRT2
+    double M_SQRT1_2
+
+    # C99 constants
+    float INFINITY
+    float NAN
+    double HUGE_VAL
+    float HUGE_VALF
+    long double HUGE_VALL
+
+    double acos(double x)
+    double asin(double x)
+    double atan(double x)
+    double atan2(double y, double x)
+    double cos(double x)
+    double sin(double x)
+    double tan(double x)
+
+    double cosh(double x)
+    double sinh(double x)
+    double tanh(double x)
+    double acosh(double x)
+    double asinh(double x)
+    double atanh(double x)
+
+    double hypot(double x, double y)
+
+    double exp(double x)
+    double exp2(double x)
+    double expm1(double x)
+    double log(double x)
+    double logb(double x)
+    double log2(double x)
+    double log10(double x)
+    double log1p(double x)
+    int ilogb(double x)
+
+    double lgamma(double x)
+    double tgamma(double x)
+
+    double frexp(double x, int* exponent)
+    double ldexp(double x, int exponent)
+
+    double modf(double x, double* iptr)
+    double fmod(double x, double y)
+    double remainder(double x, double y)
+    double remquo(double x, double y, int *quot)
+    double pow(double x, double y)
+    double sqrt(double x)
+    double cbrt(double x)
+
+    double fabs(double x)
+    double ceil(double x)
+    double floor(double x)
+    double trunc(double x)
+    double rint(double x)
+    double round(double x)
+    double nearbyint(double x)
+    double nextafter(double, double)
+    double nexttoward(double, long double)
+
+    long long llrint(double)
+    long lrint(double)
+    long long llround(double)
+    long lround(double)
+
+    double copysign(double, double)
+    float copysignf(float, float)
+    long double copysignl(long double, long double)
+
+    double erf(double)
+    float erff(float)
+    long double erfl(long double)
+    double erfc(double)
+    float erfcf(float)
+    long double erfcl(long double)
+
+    double fdim(double x, double y)
+    double fma(double x, double y)
+    double fmax(double x, double y)
+    double fmin(double x, double y)
+    double scalbln(double x, long n)
+    double scalbn(double x, int n)
+
+    double nan(const char*)
+    
+    bint isfinite(long double)
+    bint isnormal(long double)
+    bint isnan(long double)
+    bint isinf(long double)