Solaris shell chokes on gcc/configure

[Richard Earnshaw]

The solaris shell is choking on the recent configure.in change for the 
alpha-*-interix even if not configuring for this target.  The setting of 
target_cpu_default in there is causing the error:

checking for sys_siglist declaration in signal.h or unistd.h... (cached) no
../../../../gnusrc/egcs/gcc/configure: syntax error at line 2937: 
`target_cpu_default=$' unexpected
gnumake[1]: *** [config.status] Error 2

this needs to be quoted somehow (at least some shells, but not all, 
interpret $(...) in the same way as `...`).

Richard.