CompareAKMathAgainstMPFR: Set exponent limits globally

In the CORE-MATH codebase, not all mpfr-based math functions set the
exponents limits, some assume it is done before calling them. So let's
set it globally and remove the call to mpfr_set_emin code in exp().

Meta/Lagom/Tools/CompareAKMathAgainstMPFR/main.cpp

@@ -362,6 +362,9 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     u32 ruler_width = 72 + w + w2;
     outln("{}", MUST(String::repeated('-', ruler_width)));
 
+    // FIXME: Don't forget to update this when adding support for testing float functions.
+    CORE_MATH::set_exponent_limits();
+
     double log_sum = 0.0;
     int score_count = 0;
 

Meta/Lagom/Tools/CompareAKMathAgainstMPFR/reference_functions.cpp

@@ -9,21 +9,25 @@
 #include <mpfr.h>
 
 namespace CORE_MATH {
+
+void set_exponent_limits()
+{
+    mpfr_set_emin(-1073);
+    mpfr_set_emax(1024);
+}
+
 // These functions are taken from the CORE-MATH project.
 // https://gitlab.inria.fr/core-math/core-math/-/blob/master/src/binary64/
 
 double exp(double x)
 {
     mpfr_t y;
-    mpfr_exp_t emin = mpfr_get_emin();
-    mpfr_set_emin(-1073);
     mpfr_init2(y, 53);
     mpfr_set_d(y, x, MPFR_RNDN);
     int inex = mpfr_exp(y, y, MPFR_RNDN);
     mpfr_subnormalize(y, inex, MPFR_RNDN);
     double ret = mpfr_get_d(y, MPFR_RNDN);
     mpfr_clear(y);
-    mpfr_set_emin(emin);
     return ret;
 }
 

Meta/Lagom/Tools/CompareAKMathAgainstMPFR/reference_functions.h

@@ -8,6 +8,8 @@
 
 namespace CORE_MATH {
 
+void set_exponent_limits();
+
 double exp(double x);
 double log(double x);