Small Warnings Refactor (#4477)

* Disable all warnings, even in release, on the `src` directory.
Resolve math macro duplication warnings.

* Suppress LUS warnings.

* Modify it to utilize a variable that defaults on but can be specified in command line to disable it.
Prevet total compile option overwrite for LUS.

* Remove unnecessary unset and cache parameters.

* Document warnings flag in BUILDING.md

CMakeLists.txt

@@ -9,6 +9,18 @@ project(Ship VERSION 8.0.6 LANGUAGES C CXX)
 include(CMake/soh-cvars.cmake)
 include(CMake/lus-cvars.cmake)
 
+option(SUPPRESS_WARNINGS "Suppress warnings in LUS and src (decomp)" ON)
+if(SUPPRESS_WARNINGS)
+    MESSAGE("Suppressing warnings in LUS and src")
+    if(MSVC)
+        set(WARNING_OVERRIDE /w)
+    else()
+        set(WARNING_OVERRIDE -w)
+    endif()
+else()
+    MESSAGE("Skipping warning suppression")
+endif()
+
 set(NATO_PHONETIC_ALPHABET
   "Alfa" "Bravo" "Charlie" "Delta" "Echo" "Foxtrot" "Golf" "Hotel"
   "India" "Juliett" "Kilo" "Lima" "Mike" "November" "Oscar" "Papa"
@@ -148,6 +160,7 @@ add_compile_definitions(CONTROLLERBUTTONS_T=uint32_t)
 # Sub-projects
 ################################################################################
 add_subdirectory(libultraship ${CMAKE_BINARY_DIR}/libultraship)
+target_compile_options(libultraship PRIVATE "${WARNING_OVERRIDE}")
 add_subdirectory(ZAPDTR/ZAPD ${CMAKE_BINARY_DIR}/ZAPD)
 add_subdirectory(OTRExporter)
 add_subdirectory(soh)