[Bug target/52122] [4.6/4.7/4.8 Regression] incorrect ln -s replacement for mingw like targets in configure files

[andris.pavenis at iki dot fi]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52122

--- Comment #36 from Andris Pavenis <andris.pavenis at iki dot fi> 2013-02-14 04:25:17 UTC ---
This way does not work for DJGPP v2.03 (version v2.04pre is OK).

For DJGPP v2.03:

AC_PROG_LN_S tries 'ln -s', which do not work, after that it falls back to
simple
'ln' which creates copy of file (acts as 'cp'). As the result we'll getting
LN_S=ln in Makefile

Correct way should be detecting whether ln -s works for directories in
configure script and adding corresponding substitution for Makefile.in for
LN_S_RECURSIVE like

LN_S_RECURSIVE=@LN_S_RECURSIVE@

Tests could look like:
- create directory and file in the it
- try to create symlink to directory and look whether it succeeds
- check for presence of the file through symlink

Less pedantic way could be avoiding using file in subdirectory and relaying on
success of 'ln -s' only.