Revert LICENSE.md back to LICENSE.

Nobody seems to use md for this, and I bet there are crawlers and whatnot
that look specifically for LICENSE. We don't use any formatting, so who
cares, stick to the standard.

All the other text files, such as CHANGES.md, INSTALL.md, README.md, etc.,
will stay markdown.

CMakeLists.txt

@@ -611,8 +611,8 @@ set (CPACK_PACKAGE_VENDOR "Sony Pictures Imageworks")
 set (CPACK_PACKAGE_DESCRIPTION_SUMMARY "OpenShadingLanguage is...")
 set (CPACK_PACKAGE_DESCRIPTION_FILE "${PROJECT_SOURCE_DIR}/src/doc/Description.txt")
 set (CPACK_PACKAGE_FILE_NAME OSL-${OSL_LIBRARY_VERSION_MAJOR}.${OSL_LIBRARY_VERSION_MINOR}.${OSL_LIBRARY_VERSION_PATCH}-${platform})
-file (COPY "${PROJECT_SOURCE_DIR}/LICENSE.md" DESTINATION "${CMAKE_BINARY_DIR}")
-file (RENAME "${CMAKE_BINARY_DIR}/LICENSE.md" "${CMAKE_BINARY_DIR}/License.txt")
+file (COPY "${PROJECT_SOURCE_DIR}/LICENSE" DESTINATION "${CMAKE_BINARY_DIR}")
+file (RENAME "${CMAKE_BINARY_DIR}/LICENSE" "${CMAKE_BINARY_DIR}/License.txt")
 set (CPACK_RESOURCE_FILE_LICENSE "${CMAKE_BINARY_DIR}/License.txt")
 file (COPY "${PROJECT_SOURCE_DIR}/README.md" DESTINATION "${CMAKE_BINARY_DIR}")
 file (RENAME "${CMAKE_BINARY_DIR}/README.md" "${CMAKE_BINARY_DIR}/Readme.txt")