fix: handle asinpi for mpfr < 4.2.0

Author: hulxv

libc/utils/MPFRWrapper/MPCommon.cpp

@@ -107,8 +107,17 @@ MPFRNumber MPFRNumber::asinh() const {
 
 MPFRNumber MPFRNumber::asinpi() const {
   MPFRNumber result(*this);
+#if 0 && (MPFR_VERSION >= MPFR_VERSION_NUM(4, 2, 0))
   mpfr_asinpi(result.value, value, mpfr_rounding);
   return result;
+#else
+  MPFRNumber value_asin(0.0, 1280);
+  mpfr_asin(value_asin.value, value, MPFR_RNDN);
+  MPFRNumber value_pi(0.0, 1280);
+  mpfr_const_pi(value_pi.value, MPFR_RNDN);
+  mpfr_div(result.value, value_asin.value, value_pi.value, mpfr_rounding);
+  return result;
+#endif
 }
 
 MPFRNumber MPFRNumber::atan() const {