mstl: Replace gamma with lgamma

gamma is a non-standard extension in the GNU libc, see https://www.gnu.org/software/libc/manual/html_node/Special-Functions.html#index-gamma
And being non-standard, it may give different results on different systems, see https://stackoverflow.com/questions/18116376/what-is-the-definition-for-gammadouble-x-and-why-is-it-different-on-two-gcc-ve 😱

src/mstl/math2/analysis/special functions.cpp

@@ -37,7 +37,7 @@ double Gamma(double N){ return tgamma(N);}
         }*/
 
 // see Numerical Recipes for the algorithm
-double logGamma(double N){ return gamma(N);}
+double logGamma(double N){ return lgamma(N);}
        /*{ if(N<0.){ throw NEGATIVE_NUMBER("logGamma(double)");}
          double ser; double n=N;
          double c[6]={ 76.18009172947146,-86.50532032941677, 24.01409824083091,