Tests: Add RunCMake.GNUInstallDirs case for get_absolute_install_dir

Tests/RunCMake/GNUInstallDirs/GetAbs-stderr.txt

@@ -0,0 +1,12 @@
+^PROJ1_FULL_BINDIR='/usr/bin'
+CMake Warning \(dev\) at [^
+]*/Modules/GNUInstallDirs.cmake:[0-9]+ \(message\):
+  GNUInstallDirs_get_absolute_install_dir called without third argument.
+  Using \${dir} from the caller's scope for compatibility with CMake 3.19 and
+  below.
+Call Stack \(most recent call first\):
+  GetAbs.cmake:10 \(GNUInstallDirs_get_absolute_install_dir\)
+  CMakeLists.txt:3 \(include\)
+This warning is for project developers.  Use -Wno-dev to suppress it.
++
+PROJ2_FULL_BINDIR='/usr/bin'$

Tests/RunCMake/GNUInstallDirs/GetAbs.cmake

@@ -0,0 +1,11 @@
+set(CMAKE_SIZEOF_VOID_P 8)
+set(CMAKE_LIBRARY_ARCHITECTURE "arch")
+set(CMAKE_INSTALL_PREFIX /usr)
+include(GNUInstallDirs)
+
+GNUInstallDirs_get_absolute_install_dir(PROJ1_FULL_BINDIR CMAKE_INSTALL_BINDIR BINDIR)
+message("PROJ1_FULL_BINDIR='${PROJ1_FULL_BINDIR}'")
+
+set(dir BINDIR)
+GNUInstallDirs_get_absolute_install_dir(PROJ2_FULL_BINDIR CMAKE_INSTALL_BINDIR)
+message("PROJ2_FULL_BINDIR='${PROJ2_FULL_BINDIR}'")

Tests/RunCMake/GNUInstallDirs/RunCMakeTest.cmake

@@ -21,4 +21,5 @@ foreach(case
   unset(RunCMake-stderr-file)
 endforeach()
 
+run_cmake(GetAbs)
 run_cmake(NoSystem)