gh-38021: `build/pkgs/flint/spkg-configure.m4`: Reject broken FLINT package on homebrew
    
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Fixes
#38020 (comment)

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URL: #38021
Reported by: Matthias Köppe
Reviewer(s): Kwankyu Lee, Matthias Köppe

Author: Release Manager

build/pkgs/flint/spkg-configure.m4

@@ -1,6 +1,6 @@
 SAGE_SPKG_CONFIGURE([flint], [
     SAGE_SPKG_DEPCHECK([mpfr], [
-        AC_CHECK_HEADER(flint/flint.h, [dnl
+        AC_CHECK_HEADERS([flint/flint.h flint/padic.h], [dnl
           dnl gr_get_fexpr appears in Flint 3.0
           AC_SEARCH_LIBS([gr_get_fexpr], [flint], [dnl
             dnl Assume Flint 3.2 is too new