configury: fix lt_dladvise_init grep test

Change the CPPFLAGS to just -I$srcdir, and change the include file to
check to be just opal/libltdl/ltdl.h.  Do this because the CPPFLAGS
are passed to the preprocessor, and the C program that is passed
through the preprocessor is basically:

    #include <opal/libltdl/ltdl.h>

Using the proper -I covers both VPATH and non-VPATH cases.
configury: whitespace and shell quoting cleanup

Remove extra whitespace, change foo="$bar" to foo=$bar,
and change one instance of "$foo" = "1" to $foo -eq 1.
Fix singletons - still working on singleton comm_spawn
Add "-I$srcdir/opal/libltdl/" so conftest will allways set lt_dladvise.