[libc] Investigate if we can move some of the targets out of full-build-only.

[lntue]

https://github.com/llvm/llvm-project/blob/main/libc/src/CMakeLists.txt#L33

Currently the following groups are guarded behind full build mode:

• assert
• compiler
• network
• search
• setjmp
• signal
• spawn
• threads
• time

[llvmbot]

@llvm/issue-subscribers-libc

Author: None (lntue)

https://github.com/llvm/llvm-project/blob/main/libc/src/CMakeLists.txt#L33

Currently the following groups are guarded behind full build mode:

• assert
• compiler
• network
• search
• setjmp
• signal
• spawn
• threads
• time