build: add libcrypt32 dep for new mingw. Also ensure that libgcc/libstdc++ are static-linked regardless of the toolchain config

configure.ac

@@ -177,6 +177,10 @@ case $host in
      AC_CHECK_LIB([mswsock],      [main],, AC_MSG_ERROR(lib missing))
      AC_CHECK_LIB([shlwapi],      [main],, AC_MSG_ERROR(lib missing))
      AC_CHECK_LIB([iphlpapi],      [main],, AC_MSG_ERROR(lib missing))
+     AC_CHECK_LIB([crypt32],      [main],, AC_MSG_ERROR(lib missing))
+
+     AX_CHECK_LINK_FLAG([[-static-libgcc]],[LDFLAGS="$LDFLAGS -static-libgcc"])
+     AX_CHECK_LINK_FLAG([[-static-libstdc++]],[LDFLAGS="$LDFLAGS -static-libstdc++"])
 
      AC_PATH_PROG([MAKENSIS], [makensis], none)
      if test x$MAKENSIS = xnone; then