Disable LTO and static stacks for all crt builtins

These functions can be called from floating point builtins, which
violates the implicit attribute leaf on them. The floating point
builtins shouldn't be brought in summarily to LTO, since they may
reserve ZP and static stack space even if unused. The same logic broadly
applies to all CRT builtins, so until we have a better solution, pull
all of them out of LTO.

mos-platform/common/crt/CMakeLists.txt

@@ -11,9 +11,11 @@ add_platform_library(common-crt
   shift.cc
   rotate.cc
 )
-# Don't pull in stack pointer init unnecessarily.
-# This can be called in an interrupt.
-set_property(SOURCE divmod-large.cc PROPERTY COMPILE_OPTIONS -fno-lto -fno-static-stack)
+
+# Disable LTO for builtins since they may otherwise take up ZP and static
+# spance even if unused. Disable static stacks, since they are not LTOed, and
+# they may be called within interrupts.
+target_compile_options(common-crt PRIVATE -fno-lto -fno-static-stack)
 
 # Merge the builtins library from llvm-mos into libcrt.
 get_filename_component(compiler_dir ${CMAKE_C_COMPILER} DIRECTORY)