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

[dominiq at lps dot ens.fr]

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

--- Comment #19 from Dominique d'Humieres <dominiq at lps dot ens.fr> 2013-02-12 17:51:13 UTC ---
This breaks bootstrap on x86_64-apple-darwin10:

...

test -f stamp-libada || \
    make -C ../.././gcc/ada "MAKEOVERRIDES=" "LDFLAGS=" "LN_S=ln -s"
"SHELL=/bin/sh" "GNATLIBFLAGS=-W -Wall -gnatpg -nostdinc " "GNATLIBCFLAGS=-g
-O2 " "GNATLIBCFLAGS_FOR_C=-W -Wall -g -O2 -fexceptions -DIN_RTS
-DHAVE_GETIPINFO " "PICFLAG_FOR_TARGET=-fno-common" "THREAD_KIND=native"
"TRACE=no" "MULTISUBDIR="
"libsubdir=/opt/gcc/gcc4.8w/lib/gcc/x86_64-apple-darwin10.8.0/4.8.0"
"objext=.o" "prefix=/opt/gcc/gcc4.8w" "exeext=.exeext.should.not.be.used "
'CC=the.host.compiler.should.not.be.needed'
"GCC_FOR_TARGET=/opt/gcc/build_w/./gcc/xgcc -B/opt/gcc/build_w/./gcc/
-B/opt/gcc/gcc4.8w/x86_64-apple-darwin10.8.0/bin/
-B/opt/gcc/gcc4.8w/x86_64-apple-darwin10.8.0/lib/ -isystem
/opt/gcc/gcc4.8w/x86_64-apple-darwin10.8.0/include -isystem
/opt/gcc/gcc4.8w/x86_64-apple-darwin10.8.0/sys-include   " "CFLAGS=-g -O2"
gnatlib-shared \
    && touch stamp-libada
rm -rf adainclude
rm -rf adalib
../.././gcc/ada/rts adainclude
make[2]: ../.././gcc/ada/rts: Permission denied
make[2]: *** [gnatlib-shared] Error 1
make[1]: *** [all-target-libada] Error 2
make: *** [all] Error 2