ENH: do not check for gnu for visual studio

Modules/CMakeDetermineCCompiler.cmake

@@ -45,6 +45,12 @@ IF(NOT CMAKE_RANLIB)
 ENDIF(NOT CMAKE_RANLIB)
 MARK_AS_ADVANCED(CMAKE_RANLIB)
 
+# do not test for GNU if the generator is visual studio
+IF(${CMAKE_GENERATOR} MATCHES "Visual Studio")
+  SET(CMAKE_COMPILER_IS_GNUCC_RUN 1)
+ENDIF(${CMAKE_GENERATOR} MATCHES "Visual Studio") 
+
+
 IF(NOT CMAKE_COMPILER_IS_GNUCC_RUN)
   # test to see if the c compiler is gnu
   

Modules/CMakeDetermineCXXCompiler.cmake

@@ -38,6 +38,11 @@ IF(NOT CMAKE_CXX_COMPILER)
 ENDIF(NOT CMAKE_CXX_COMPILER)
 MARK_AS_ADVANCED(CMAKE_CXX_COMPILER)
 
+# do not test for GNU if the generator is visual studio
+IF(${CMAKE_GENERATOR} MATCHES "Visual Studio")
+  SET(CMAKE_COMPILER_IS_GNUCXX_RUN 1)
+ENDIF(${CMAKE_GENERATOR} MATCHES "Visual Studio")
+
 IF(NOT CMAKE_COMPILER_IS_GNUCXX_RUN)
   # test to see if the cxx compiler is gnu
   SET(CMAKE_COMPILER_IS_GNUCXX_RUN 1)

Modules/CMakeDetermineFortranCompiler.cmake

@@ -69,6 +69,11 @@ IF(NOT CMAKE_RANLIB)
 ENDIF(NOT CMAKE_RANLIB)
 MARK_AS_ADVANCED(CMAKE_RANLIB)
 
+# do not test for GNU if the generator is visual studio
+IF(${CMAKE_GENERATOR} MATCHES "Visual Studio")
+  SET(CMAKE_COMPILER_IS_GNUG77_RUN 1)
+ENDIF(${CMAKE_GENERATOR} MATCHES "Visual Studio") 
+
 IF(NOT CMAKE_COMPILER_IS_GNUG77_RUN)
   # test to see if the Fortran compiler is gnu