Avoid adding -O2 to CFLAGS; gentoo bug #943226
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7372bab..665ed23 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -555,7 +555,6 @@ if ("x${CMAKE_CXX_COMPILER_ID}" STREQUAL "xMSVC" OR "x${CMAKE_CXX_COMPILER_FRONT
 
   list(APPEND BLEND2D_PRIVATE_CFLAGS_REL
     -GS-                          # [-] Buffer security-check.
-    -O2                           # [+] Favor speed over size.
     -Oi)                          # [+] Generate Intrinsic Functions.
 
   if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang")
@@ -564,7 +563,6 @@ if ("x${CMAKE_CXX_COMPILER_ID}" STREQUAL "xMSVC" OR "x${CMAKE_CXX_COMPILER_FRONT
 elseif ("${CMAKE_CXX_COMPILER_ID}" MATCHES "GNU|Clang")
   list(APPEND BLEND2D_PRIVATE_CFLAGS -Wall -Wextra)
   list(APPEND BLEND2D_PRIVATE_CFLAGS -fno-exceptions -fno-rtti -fno-math-errno)
-  list(APPEND BLEND2D_PRIVATE_CFLAGS_REL -O2)
 
   if (NOT "${CMAKE_SYSTEM_NAME}" STREQUAL "iOS")
     # Disable these flags in case somebody uses -ffast-math globally.