Install to a better location.
Remove hardcoded optimization flags.

Index: CMakeLists.txt
--- CMakeLists.txt.orig
+++ CMakeLists.txt
@@ -86,9 +86,9 @@ if(MSVC)
 else()
     set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -Wextra -Wno-unused-parameter -Wformat -pedantic -Wvla")
     set(CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG} -ggdb -Werror -fno-omit-frame-pointer")
-    set(CMAKE_C_FLAGS_RELWITHDEBINFO "${CMAKE_C_FLAGS_RELWITHDEBINFO} -g -O2 -fno-omit-frame-pointer -DNDEBUG")
-    set(CMAKE_C_FLAGS_RELEASE "${CMAKE_C_FLAGS_RELEASE} -O2 -DNDEBUG")
-    set(CMAKE_C_FLAGS_MINSIZEREL "${CMAKE_C_FLAGS_MINSIZEREL} -Os -DNDEBUG")
+    set(CMAKE_C_FLAGS_RELWITHDEBINFO "${CMAKE_C_FLAGS_RELWITHDEBINFO} -g -fno-omit-frame-pointer -DNDEBUG")
+    set(CMAKE_C_FLAGS_RELEASE "${CMAKE_C_FLAGS_RELEASE} -DNDEBUG")
+    set(CMAKE_C_FLAGS_MINSIZEREL "${CMAKE_C_FLAGS_MINSIZEREL} -DNDEBUG")
 endif()
 
 # Enable AddressSanitizer if requested
@@ -478,8 +478,8 @@ else()
     # On unixy systems, follow standard.
     install(TARGETS openomf RUNTIME DESTINATION bin COMPONENT Binaries)
     install(FILES ${DOC_FILES} resources/openomf.bk resources/gamecontrollerdb/gamecontrollerdb.txt resources/icons/openomf.png
-        DESTINATION share/games/openomf/
+        DESTINATION share/openomf/
         COMPONENT Data
     )
-    install(DIRECTORY shaders/ DESTINATION share/games/openomf/shaders COMPONENT Data)
+    install(DIRECTORY shaders/ DESTINATION share/openomf/shaders COMPONENT Data)
 endif()
