Fix build failure with GCC 10 due to duplicate definitions.  It can be
reproduced on older compilers with -fno-common.

Fix taken from Gentoo: https://bugs.gentoo.org/705898

--- a/src/parseopt.c
+++ b/src/parseopt.c
@@ -255,8 +255,6 @@ print_option_descr (const char *descr, size_t lmargin, size_t rmargin)
 }
 
 char *parseopt_program_name;
-char *parseopt_program_doc;
-char *parseopt_program_args;
 const char *program_bug_address = "<" PACKAGE_BUGREPORT ">";
 void (*parseopt_help_hook) (FILE *stream);
 
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<tr><td><span title='2021-06-13 20:46:01 +0200'>2021-06-13</span></td><td><a href='/guix/commit/bootstrap?id=bd02e50a02ceed914135dba1e69e4457e489cf86'>bootstrap: Simplify search for translation languages.</a><span class='msg-avail'>...<span class='msg-tooltip'>Extend the sed script to also behave like "basename",
saving the addtional call of "xargs basename".

* bootstrap (langs): Extend sed scripts, remove running xargs.
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