Add sanity check on /usr/include/iso/math_iso.h problem on build machines (latest libm patch)

Latest libm patch causes bits built on machines having it to not work on any machines
that don't have the patch.

So far, the solution has been to be very careful with build machines, and
if the latest libm patch gets onto the machine, we sneak in as root and replace
/usr/include/iso/math_iso.h with the older copy.

Turns out that it's tricky to build anything that has a problem, you have to
actually pass a 'float' argument to a math function in C++, and if your source
has included this new math_iso.h, only then will you get a dependence on an
external in libm.so that only exists on machines with the new libm patch.
There was one place in libjvm.so source that did this, and the author suggested
that he might change it, so I don't know if the problem persists.

The libm patch is strictly a build machine issue that can create a runtime
failure, not a runtime issue, machines with this new libm patch run fine.

We should add a makefile sanity check against the math_iso.h file.
###@###.### 2005-03-14 17:57:32 GMT