"ac_fn_c_try_run" clause not executing.

[alexandre schenberg]

Hi. Running the configure script of an old gimp, a line containing the 
"ac_fn_c_try_run" does not evaluate as true.

This leads a certain variable to be set as true, which makes the gtk's 
detection test to fail.

The problem is likely related to something in pkg-config's use in configure, as 
another line that directly invokes pkg-config, also does not evaluate as true, 
which also ends up setting this variable as true and causes the detection test 
to fail.

So I am trying to understand what this function does and hence how/why it can 
fail.

The line is: "if ac_fn_c_try_run "$LINENO"; then :"

I attached the full gtk detection test.

gtk_test.sh
Description: Text Data