Minimally patch libtheora's ancient config.guess to support mips64.

--- libtheora/config.guess.orig	2009-02-23 22:50:50.000000000 -0500
+++ libtheora/config.guess	2013-10-31 23:49:48.155999944 -0400
@@ -798,25 +798,24 @@
     m68*:Linux:*:*)
 	echo ${UNAME_MACHINE}-unknown-linux-gnu
 	exit 0 ;;
-    mips:Linux:*:*)
+    mips:Linux:*:* | mips64:Linux:*:*)
 	eval $set_cc_for_build
 	sed 's/^	//' << EOF >$dummy.c
 	#undef CPU
-	#undef mips
-	#undef mipsel
+	#undef ${UNAME_MACHINE}
+	#undef ${UNAME_MACHINE}el
 	#if defined(__MIPSEL__) || defined(__MIPSEL) || defined(_MIPSEL) || defined(MIPSEL)
-	CPU=mipsel
+	CPU=${UNAME_MACHINE}el
 	#else
 	#if defined(__MIPSEB__) || defined(__MIPSEB) || defined(_MIPSEB) || defined(MIPSEB)
-	CPU=mips
+	CPU=${UNAME_MACHINE}
 	#else
 	CPU=
 	#endif
 	#endif
 EOF
-	eval `$CC_FOR_BUILD -E $dummy.c 2>/dev/null | grep ^CPU=`
-	rm -f $dummy.c && rmdir $tmpdir
-	test x"${CPU}" != x && echo "${CPU}-pc-linux-gnu" && exit 0
+	eval `$CC_FOR_BUILD -E $dummy.c 2>/dev/null | grep '^CPU'`
+	test x"${CPU}" != x && { echo "${CPU}-unknown-linux-gnu"; exit 0; }
 	;;
     ppc:Linux:*:*)
 	echo powerpc-unknown-linux-gnu
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<div class='path'>path: <a href='/guix/log/?id=b6c445931e85c07286a79bc9c80fdc956d58b1e2'>root</a>/<a href='/guix/log/gnu?id=b6c445931e85c07286a79bc9c80fdc956d58b1e2'>gnu</a>/<a href='/guix/log/gnu/build?id=b6c445931e85c07286a79bc9c80fdc956d58b1e2'>build</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/build?id=b6c445931e85c07286a79bc9c80fdc956d58b1e2&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-05-29 12:20:15 +0200'>2020-05-29</span></td><td><a href='/guix/commit/gnu/build?id=72d1562a4da8909b1990687d6f33b543bd215541'>build: image: Fix initialize-efi-partition docstring.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/build/image.scm (initialize-efi-partition): Turn BOOTLOADER-PACKAGE into
GRUB-EFI.
</span></span></td><td>Mathieu Othacehe</td></tr>
<tr><td><span title='2020-05-29 08:43:20 +0200'>2020-05-29</span></td><td><a href='/guix/commit/gnu/build?id=05f37c16a3b159e58ce7343383b44073bd6cac9f'>image: Use grub-efi to install the EFI bootloader.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/build/image.scm (initialize-efi-partition): Rename bootloader-package
argument to grub-efi.
* gnu/system/image.scm (system-disk-image): Adapt accordingly to pass
grub-efi package.
</span></span></td><td>Mathieu Othacehe</td></tr>
<tr><td><span title='2020-05-29 08:40:03 +0200'>2020-05-29</span></td><td><a href='/guix/commit/gnu/build?id=9c1adb240016261d6263e8d7d0308040542f3c60'>image: Add bootloader installation support.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/build/image.scm (initialize-root-partition): Add bootloader-package and
bootloader-installer arguments. Run the bootloader-installer if defined.
* gnu/system/image.scm (system-disk-image): Adapt the partition initializer
call accordingly.
</span></span></td><td>Mathieu Othacehe</td></tr>
<tr><td><span title='2020-05-26 17:16:42 +0200'>2020-05-26</span></td><td><a href='/guix/commit/gnu/build?id=bd3716f6fee127562935d86ff7f641197366769c'>image: Add partition file-system options support.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/image.scm (&lt;partition&gt;)[file-system-options]: New field,
(partition-file-system-options): new exported procedure.
* gnu/system/image.scm (partition-&gt;gexp): Adapt accordingly.
* gnu/build/image.scm (sexp-&gt;partition): Also adapt accordingly,
(make-ext-image): and pass file-system options to mke2fs.
</span></span></td><td>Mathieu Othacehe</td></tr>
<tr><td><span title='2020-05-26 09:57:10 +0200'>2020-05-26</span></td><td><a href='/guix/commit/gnu/build?id=16f9124d1fec7b40cdac189346e0d5021e43122b'>build: image: Add support for EXT2 and EXT3 file-systems.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/build/image.scm (make-ext4-image): Rename to ...
(make-ext-image): ... it, and pass the file-system type to mke2fs,
(make-partition-image): Adapt to call "make-ext-image" if the partition
file-system is prefixed by "ext".
</span></span></td><td>Mathieu Othacehe</td></tr>