i18n: proposed command missing leading dash

Add missing leading dash to proposed commands in french output when
using the command:
    git branch --set-upstream remotename/branchname
and when upstream is gone

Signed-off-by: Sandy Carter <sandy.carter@savoirfairelinux.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

po/fr.po

@@ -1075,7 +1075,7 @@ msgstr "Votre branche est basée sur '%s', mais la branche amont a disparu.\n"
 
 #: remote.c:1875
 msgid "  (use \"git branch --unset-upstream\" to fixup)\n"
-msgstr "  (utilisez \"git branch -unset-upstream\" pour corriger)\n"
+msgstr "  (utilisez \"git branch --unset-upstream\" pour corriger)\n"
 
 #: remote.c:1878
 #, c-format
@@ -3266,7 +3266,7 @@ msgstr "    git branch -d %s\n"
 #: builtin/branch.c:1027
 #, c-format
 msgid "    git branch --set-upstream-to %s\n"
-msgstr "    git branch -set-upstream-to %s\n"
+msgstr "    git branch --set-upstream-to %s\n"
 
 #: builtin/bundle.c:47
 #, c-format