Added glm.cppm to CXX_MODULES target_sources

[sweet-niamhy]

Description

• Added the glm.cppm file to the public CXX_MODULES fileset for the glm target in order to make the glm module available to projects.
• The cppm file was originally authored here but no guidance was given for using it in a project.

This has been mentioned in an issue #1372 and in the comment #1208 (comment) so this would enable resolving of those issues.

[Diyou]

Wouldn't an intermediate target work for both glm and glm-header-only ?
Like:

add_library(glm-miu STATIC)
target_sources(glm-miu
	PUBLIC
	FILE_SET CXX_MODULES
	BASE_DIRS .
	FILES glm.cppm
)
target_link_libraries(glm-header-only INTERFACE glm-miu)

[sweet-niamhy]

Wouldn't an intermediate target work for both glm and glm-header-only ? Like:

add_library(glm-miu STATIC)
target_sources(glm-miu
	PUBLIC
	FILE_SET CXX_MODULES
	BASE_DIRS .
	FILES glm.cppm
)
target_link_libraries(glm-header-only INTERFACE glm-miu)

I tested this out and it works with GLM_BUILD_LIBRARY on and off. Thanks!

[sweet-niamhy]

I might need to work on this a while as I'm seeing some issues with different options enabled. I don't have a lot of spare time lately but will try to putter around!