Look up formfactor IMPORTED_LOCATION via IMPORTED_CONFIGURATIONS.

Upstream FindLibraries.cmake hardcodes IMPORTED_LOCATION_RELEASE +
IMPORTED_LOCATION_NOCONFIG fallbacks, which fails on distro packages
where libformfactor was built with CMAKE_BUILD_TYPE=RelWithDebInfo (the
Gentoo cmake.eclass default — its target file declares
IMPORTED_LOCATION_RELWITHDEBINFO instead). Walk the IMPORTED_CONFIGURATIONS
list and pick the first non-empty location; this handles any cmake-eclass
choice without needing to coordinate build types between consumer and
producer.

verified 2026-05-14 against bornagain-23.0 + libformfactor-0.3.2 built RelWithDebInfo.

--- a/cmake/BornAgain/FindLibraries.cmake
+++ b/cmake/BornAgain/FindLibraries.cmake
@@ -24,7 +24,17 @@

 find_package(formfactor 0.3.0 REQUIRED CONFIG)
 # absolute path is needed for deployment in Python wheel
-get_target_property(formfactor_LIBRARIES formfactor IMPORTED_LOCATION_RELEASE)
+# Iterate over whichever configurations the consumer-side libformfactor
+# was packaged with (Release / NOCONFIG / RelWithDebInfo / ...) rather than
+# hardcoding RELEASE+NOCONFIG; matters for distro packages built with
+# CMAKE_BUILD_TYPE=RelWithDebInfo (the Gentoo cmake.eclass default).
+get_target_property(_ff_imported_configs formfactor IMPORTED_CONFIGURATIONS)
+foreach(_ff_cfg ${_ff_imported_configs})
+    get_target_property(formfactor_LIBRARIES formfactor IMPORTED_LOCATION_${_ff_cfg})
+    if(formfactor_LIBRARIES)
+        break()
+    endif()
+endforeach()
 if(NOT formfactor_LIBRARIES)
     get_target_property(formfactor_LIBRARIES formfactor IMPORTED_LOCATION_NOCONFIG)
 endif()