You might need to look at the configure-scripts .. try grep -iw gegl *
.. to see how-and-where this test is actually done.
You see, what "configure" actually does
is to run a bunch of tests about your system-environment so that it can figure out how to build the so-called "makefiles" that actually drive the compile process. (It's part of a grander scheme called "autoconf.") This facility can therefore do things like checking for prerequisites and corequisites, and altering the "makefile"-generation process to deal with user options, environmental differences and so-on.
"Configure" scripts can include many different kinds of tests ... including this one. (I don't have a clue what "GEGL" is, nor do I have to.) The best way to figure out exactly why a test is failing
is to determine exactly what the test actually is.
The guy or gal who created that configure-script decided that, so "the only way to know for sure is to go find out."
Let me for-the-record review that little bit of voodoo that I quoted: grep -iw gegl *
- "grep" searches for strings in files.
- the string that I am looking for is 'gegl'
- the place that I am searching is "here" .. that is, "*"
- I have two options: the first one is 'i' which means "case-insensitive." I don't care if I find "gegl" or "GEGL" or "GeGl" or "gEgL" ...
- the second option is 'w' ... I'm looking for a "word" that's surrounded on both sides by a whitespace character (or by the beginning or the end of a line of text). That's to give me matches for "GegL" but not "omniGegLplex" (whatever that is...)