ushare: fix linking issue with gcc 5.x

Fixes:
http://autobuild.buildroot.net/results/1d4/1d4d621f3bd7862a75bd7e95e275ccb6694b54c9/
http://autobuild.buildroot.net/results/140/140767a7437b60a62f553ab49c104c37a4949c6c/
http://autobuild.buildroot.net/results/a88/a88ae349d4d7cdff4f15c8ad9e3a1eac74dc6c4b/
http://autobuild.buildroot.net/results/599/59946c728593502e4a17cb7e2d75eabac54db537/

And many more.

GCC5 defaults to -std=gnu11, which has different semantics for inline than
previous versions:

https://gcc.gnu.org/gcc-5/porting_to.html



Which causes linker issues when display_headers() and start_log() are
referenced from other files.  There's no real reason why these needs to be
inline, so just drop the keyword.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>