bpo-32635: Fix a segfault when importing the crypt module with libxcrypt. (#5284)

glibc is deprecating libcrypt in favor of libxcrypt, however python assumes
that crypt.h will always be included. This change makes the header inclusion
explicit when libxcrypt is present on the system.
diff --git a/configure b/configure
index a9b0ab9..5904b54 100755
--- a/configure
+++ b/configure
@@ -7682,7 +7682,7 @@
 
 fi
 
-for ac_header in asm/types.h conio.h direct.h dlfcn.h errno.h \
+for ac_header in asm/types.h crypt.h conio.h direct.h dlfcn.h errno.h \
 fcntl.h grp.h \
 ieeefp.h io.h langinfo.h libintl.h process.h pthread.h \
 sched.h shadow.h signal.h stropts.h termios.h \