[FFmpeg-trac] #6918(build system:new): configure fails to recognize static libmp3lame

[FFmpeg]

#6918: configure fails to recognize static libmp3lame
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             Reporter:               |                     Type:  defect
  Basic.Master                       |                 Priority:  normal
               Status:  new          |                  Version:  git-
            Component:  build        |  master
  system                             |               Blocked By:
             Keywords:               |  Reproduced by developer:  0
             Blocking:               |
Analyzed by developer:  0            |
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 Distribution: Ubuntu MATE 16.04 AMD64

 When I try to build ffmpeg from git in combination with a static
 libmp3lame, configure fails with the following result:

   ERROR: libmp3lame >= 3.98.3 not found

 Used command line:
   ./configure --enable-libmp3lame

 Lame (version 3.99.5) was compiled with:
   ./configure --disable-shared

 The reason is that the presence check in "configure" (line 5856; just
 search for ">= 3.98.3") is done by compiling a minimal C program that
 invokes the library.

 However linking the static version of libmp3lame in addition to
 "-lmp3lame" (see end of the mentioned line of "configure") also requires
 "-lm" (/ffbuild/config.log shows math.h related error messages).

 To solve this, "-lm" can just be appended to the end of the mentioned
 "configure" line; afterwards, configure succeeds. Please find the simple
 patch attached.

 (the bug occured in the first place when I tried to build libav as part of
 the VLC contribs, but I also reproduced it with the most recent git
 version of stand-alone ffmpeg).

 Note that I also opened an issue at libav (unfortunately without success):
 https://bugzilla.libav.org/show_bug.cgi?id=1090

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Ticket URL: <https://trac.ffmpeg.org/ticket/6918>
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