Make FindBISON work properly with non-C locales (#11326)

Applying the patch attached to http://public.kitware.com/Bug/view.php?id=11326
It sets LC_ALL to C before calling execute_process(), so the output is
in english.

Alex

Modules/FindBISON.cmake

@@ -51,12 +51,19 @@ FIND_PROGRAM(BISON_EXECUTABLE bison DOC "path to the bison executable")
 MARK_AS_ADVANCED(BISON_EXECUTABLE)
 
 IF(BISON_EXECUTABLE)
+  # the bison commands should be executed with the C locale, otherwise
+  # the message (which are parsed) may be translated
+  SET(_Bison_SAVED_LC_ALL "$ENV{LC_ALL}")
+  SET(ENV{LC_ALL} C)
 
   EXECUTE_PROCESS(COMMAND ${BISON_EXECUTABLE} --version
     OUTPUT_VARIABLE BISON_version_output
     ERROR_VARIABLE BISON_version_error
     RESULT_VARIABLE BISON_version_result
     OUTPUT_STRIP_TRAILING_WHITESPACE)
+
+  SET(ENV{LC_ALL} ${_Bison_SAVED_LC_ALL})
+
   IF(NOT ${BISON_version_result} EQUAL 0)
     MESSAGE(SEND_ERROR "Command \"${BISON_EXECUTABLE} --version\" failed with output:\n${BISON_version_error}")
   ELSE()
@@ -115,7 +122,7 @@ IF(BISON_EXECUTABLE)
         IF("${ARGV5}" STREQUAL "VERBOSE")
           BISON_TARGET_option_verbose(${Name} ${BisonOutput} "${ARGV6}")
         ENDIF()
-      
+
         IF("${ARGV5}" STREQUAL "COMPILE_FLAGS")
           BISON_TARGET_option_extraopts("${ARGV6}")
         ENDIF()
@@ -125,10 +132,10 @@ IF(BISON_EXECUTABLE)
       LIST(APPEND BISON_TARGET_cmdopt "-d")
       STRING(REGEX REPLACE "^(.*)(\\.[^.]*)$" "\\2" _fileext "${ARGV2}")
       STRING(REPLACE "c" "h" _fileext ${_fileext})
-      STRING(REGEX REPLACE "^(.*)(\\.[^.]*)$" "\\1${_fileext}" 
+      STRING(REGEX REPLACE "^(.*)(\\.[^.]*)$" "\\1${_fileext}"
           BISON_${Name}_OUTPUT_HEADER "${ARGV2}")
       LIST(APPEND BISON_TARGET_outputs "${BISON_${Name}_OUTPUT_HEADER}")
-        
+
       ADD_CUSTOM_COMMAND(OUTPUT ${BISON_TARGET_outputs}
         ${BISON_TARGET_extraoutputs}
         COMMAND ${BISON_EXECUTABLE}
@@ -136,7 +143,7 @@ IF(BISON_EXECUTABLE)
         DEPENDS ${ARGV1}
         COMMENT "[BISON][${Name}] Building parser with bison ${BISON_VERSION}"
         WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR})
-    
+
       # define target variables
       SET(BISON_${Name}_DEFINED TRUE)
       SET(BISON_${Name}_INPUT ${ARGV1})