There are cases where inline doesn't cause inlining, but
__attribute__((always_inline)) causes inlining and improves the performance of
the code.  Having to resort to __attribute__((always_inline)) is rather ugly,
especially in code that also has to compile on other compilers.

This is filed as suggested in bug 11680 comment 4.

A testcase is attachment 4487 [details] (from bug 11680).

Steps to reproduce:
 1. Compile attachment 4487 [details] using -O2.
 2. time "<executable> original" and "<executable> slow".
 3. Modify the attachment to comment out the __attribute__((always_inline))
(and, if you want, add |inline|, although C++ says it's implied for methods
defined inside of class defitions, and it doesn't make a difference) in the
class ConvertUTF16toUTF8_slow
 4. recompile

Expected results:
 2. The two take the same amount of time.
 4. There is no change in the size of the binary.

Actual results:
 2. "slow" is faster than "original".
 4. the binary is bigger without the __attribute__((always_inline))