Modifes abs of mongodb to use std::abs

mongo_abs.patch

diff --git a/src/third_party/s2/util/math/mathutil.h b/src/third_party/s2/util/math/mathutil.h
index 0515912..8750b57 100755
--- a/src/third_party/s2/util/math/mathutil.h
+++ b/src/third_party/s2/util/math/mathutil.h
@@ -150,8 +150,8 @@ class MathUtil {
     // Discriminants below kTolerance in absolute value are considered zero
     // because changing the final bit of one of the inputs can change the
     // sign of the discriminant.
-    const double kTolerance = epsilon * max(fabs(2 * b * b), fabs(4 * a * c));
-    return (fabs(discriminant) <= kTolerance);
+    const double kTolerance = epsilon * max(std::abs(long(2 * b * b)), std::abs(long(4 * a * c)));
+    return (std::abs(long(discriminant)) <= kTolerance);
   }

   // Returns in *r1 and *r2 the roots of a "normal" quadratic equation
@@ -429,7 +429,7 @@ class MathUtil {

   // the sine cardinal function
   static double Sinc(double x) {
-    if (fabs(x) < 1E-8) return 1.0;
+    if (std::abs(long(x)) < 1E-8) return 1.0;
     return sin(x) / x;
   }

diff --git a/src/third_party/s2/util/math/mathutil.cc b/src/third_party/s2/util/math/mathutil.cc
index 10be916..e908dfd 100755
--- a/src/third_party/s2/util/math/mathutil.cc
+++ b/src/third_party/s2/util/math/mathutil.cc
@@ -118,7 +118,7 @@ bool MathUtil::RealRootsForCubic(long double const a,
   }

   long double const A =
-    -sgn(R) * pow(fabs(R) + sqrt(R_squared - Q_cubed), 1.0/3.0L);
+    -sgn(R) * pow(std::abs(long(R)) + sqrt(R_squared - Q_cubed), 1.0/3.0L);

   if (A != 0.0) {  // in which case, B from NR is zero
     *r1 = A + Q / A - a_third;