Fixed warning in CMake when MATLAB not found

cmake/modules/FindMATLAB.cmake

@@ -84,6 +84,13 @@ else()
   if((NOT DEFINED MATLAB_ROOT)
       OR ("${MATLAB_ROOT}" STREQUAL ""))
     # get path to the Matlab root directory
+    
+    execute_process(
+      COMMAND which matlab
+      OUTPUT_VARIABLE MATLAB_BIN_EXISTS
+    )
+    
+    IF (MATLAB_BIN_EXISTS)
       execute_process(
         COMMAND which matlab
         COMMAND xargs readlink
@@ -92,6 +99,7 @@ else()
         COMMAND xargs echo -n
         OUTPUT_VARIABLE MATLAB_ROOT
         )
+    ENDIF (MATLAB_BIN_EXISTS)     
   endif()
 
   # Check if this is a Mac