Fixed error where GCCXML_PATH was hard coded instead of actually searching for a program.

Added GCCXML_EXTRA_ARGS variable to work around brittle gccxml incorporation.

wrappers/CMakeLists.txt

 INCLUDE(FindJava)
 
+set(GCCXML_EXTRA_ARGS "" CACHE STRING "Additional arguments to gccxml, such as '--gccxml-compiler;msvc8'")
 SET(GCCXML_ARGS) # start empty
 FOREACH(subdir ${API_INCLUDE_DIRS})
     SET(GCCXML_ARGS ${GCCXML_ARGS} -I${subdir})
 ENDFOREACH(subdir)
+SET(GCCXML_ARGS ${GCCXML_ARGS} ${GCCXML_EXTRA_ARGS})
 
-SET(GCCXML_PATH "/usr/local/bin/gccxml" CACHE FILEPATH "Path to the gccxml executable")
+find_program(GCCXML_PATH gccxml PATH
+    /usr/local/bin
+    "C:/Program Files/gccxml 0.9/bin"
+)
 
 ADD_CUSTOM_COMMAND(OUTPUT OpenMMApi.xml COMMAND ${GCCXML_PATH} ${GCCXML_ARGS} ${CMAKE_SOURCE_DIR}/openmmapi/include/OpenMM.h -fxml=OpenMMApi.xml)
 ADD_CUSTOM_COMMAND(OUTPUT OpenMMCWrapper.h COMMAND ${JAVA_RUNTIME} -jar ${CMAKE_SOURCE_DIR}/wrappers/saxonb9-1-0-7j/saxon9.jar -t -s:OpenMMApi.xml