build/pkgs/gmp/spkg-configure.m4: Check the actual GMP version, to ma…

…tch check in FLINT 3.1

build/pkgs/gmp/spkg-configure.m4

@@ -2,6 +2,26 @@ SAGE_SPKG_CONFIGURE([gmp], [
            sage_spkg_install_gmp=no
             AC_CHECK_HEADER(gmp.h, [], [sage_spkg_install_gmp=yes])
             AC_CHECK_HEADER(gmpxx.h, [], [sage_spkg_install_gmp=yes])
+            # Check that GMP >= 6.2.1; this test is copied from FLINT.
+            AC_MSG_CHECKING([if version of GMP is greater than 6.2.1])
+            AC_COMPILE_IFELSE([
+                AC_LANG_PROGRAM(
+                    [[#include <gmp.h>
+                     ]],
+                    [[#if (__GNU_MP_VERSION < 6) \
+                       || (__GNU_MP_VERSION == 6 && __GNU_MP_VERSION_MINOR < 2) \
+                       || (__GNU_MP_VERSION == 6 && __GNU_MP_VERSION_MINOR == 2 && __GNU_MP_VERSION_PATCHLEVEL < 1)
+                      # error GMP version 6.2.1 or later is required
+                      #endif
+                     ]]
+                )], [dnl
+                    AC_MSG_RESULT([yes])
+                ], [dnl
+                    AC_MSG_RESULT([no])
+                    sage_spkg_install_gmp=yes
+                ])
+            dnl The test above uses the headers only. To protect against header/library
+            dnl mismatches, we now check for a function.
             dnl mpn_gcd_11 appeared in GMP 6.2.1
             dnl It is undocumented but is used by Flint when built with default
             dnl flags.