cmake: Tidy compiler options.

Prior to this patch there was some long line of unreadable compiler
options. Now the long lines are deduplicated and there is only one
option per line to ease reading/maintenance.

CMakeLists.txt

@@ -138,22 +138,42 @@ set(CMAKE_CXX_LINK_FLAGS "-Wl,--hash-style=gnu,-z,relro,-z,now,-z,noexecstack")
 # This will need to be revisited when the Loader supports RPATH/RUN_PATH.
 set(CMAKE_SKIP_RPATH TRUE)
 
-if (${CMAKE_HOST_SYSTEM_NAME} MATCHES SerenityOS)
+add_compile_options(-Wformat=2)
+add_compile_options(-fdiagnostics-color=always)
+
+if (NOT ${CMAKE_HOST_SYSTEM_NAME} MATCHES SerenityOS)
  # FIXME: Something makes this go crazy and flag unused variables that aren't flagged as such when building with the toolchain.
  # Disable -Werror for now.
- add_compile_options(-Wno-unknown-warning-option -Wall -Wextra -Wmissing-declarations -Wformat=2 -fdiagnostics-color=always)
-else()
- add_compile_options(-Wno-unknown-warning-option -Wall -Wextra -Werror -Wmissing-declarations -Wformat=2 -fdiagnostics-color=always)
+ add_compile_options(-Werror)
 endif()
 
-add_compile_options(-g1 -fno-exceptions -fstack-protector-strong -Wno-address-of-packed-member -Wundef -Wcast-qual -Wwrite-strings -Wimplicit-fallthrough -Wno-nonnull-compare -Wno-deprecated-copy -Wno-expansion-to-defined)
+add_compile_options(-Wall)
+add_compile_options(-Wextra)
+
+add_compile_options(-Wno-address-of-packed-member)
+add_compile_options(-Wcast-qual)
+add_compile_options(-Wno-deprecated-copy)
+add_compile_options(-Wno-expansion-to-defined)
+add_compile_options(-Wimplicit-fallthrough)
+add_compile_options(-Wmissing-declarations)
+add_compile_options(-Wno-nonnull-compare)
+add_compile_options(-Wno-unknown-warning-option)
+add_compile_options(-Wundef)
+add_compile_options(-Wwrite-strings)
+
 add_compile_options(-ffile-prefix-map=${CMAKE_SOURCE_DIR}=.)
+add_compile_options(-fno-exceptions)
+add_compile_options(-fstack-protector-strong)
+add_compile_options(-g1)
 
 if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
- add_compile_options(-fconcepts -Wno-literal-suffix)
+ add_compile_options(-Wno-literal-suffix)
+
+ add_compile_options(-fconcepts)
  add_compile_options(-fstack-clash-protection)
 elseif ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang")
- add_compile_options(-Wno-overloaded-virtual -Wno-user-defined-literals)
+ add_compile_options(-Wno-overloaded-virtual)
+ add_compile_options(-Wno-user-defined-literals)
 endif()
 
 add_compile_definitions(DEBUG SANITIZE_PTRS)