[OpenMP][FIX] Fixup test that doesn't work with lit's env substitute

Author: jdoerfert

openmp/libomptarget/test/offloading/shared_lib_fp_mapping.c

@@ -1,7 +1,7 @@
 // clang-format off
 // RUN: %clang-generic -fPIC -shared %S/../Inputs/declare_indirect_func.c -o %T/liba.so  -fopenmp-version=51
-// RUN: %libomptarget-compile-generic -L %T -l a -o %t  -fopenmp-version=51
-// RUN: env LIBOMPTARGET_INFO=32 LD_LIBRARY_PATH=%T:$LD_LIBRARY_PATH %t | %fcheck-generic
+// RUN: %libomptarget-compile-generic -rpath %T -L %T -l a -o %t  -fopenmp-version=51
+// RUN: env LIBOMPTARGET_INFO=32 %t 2>&1 | %fcheck-generic
 // clang-format on
 
 #include <stdio.h>