Add new intrinsic LDC_no_inline.

LDC_no_inline is a complementary intrinsic to LDC_allow_inline.
It tells the LLVM optimizer to not inline a function. This can be useful if inlining creates incorrect code.
A possible application is `core.thread.getStackTop()`. In case the intrinsic `llvm_frameaddress` is used the function must not be inlined. Other possible wrong code is produced.