This error could be caused by configure scripts being run with -Werror
-Wall, which would lead to libcurl being detected as unusable.

---
 docs/libcurl/libcurl.m4 |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
diff --git a/docs/libcurl/libcurl.m4 b/docs/libcurl/libcurl.m4
index 01a0575..8cada05 100644
--- a/docs/libcurl/libcurl.m4
+++ b/docs/libcurl/libcurl.m4
@@ -157,6 +157,7 @@ x=CURLOPT_FILE;
 x=CURLOPT_ERRORBUFFER;
 x=CURLOPT_STDERR;
 x=CURLOPT_VERBOSE;
+if (x) ;
 ])],libcurl_cv_lib_curl_usable=yes,libcurl_cv_lib_curl_usable=no)
 
            CPPFLAGS=$_libcurl_save_cppflags
-- 
1.7.6.4
--=-sgcCt0l9ZRr8/V/GPw9L
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--=-sgcCt0l9ZRr8/V/GPw9L--