Use -ffast-math only for compilation

Updates #488
Closes #554

CMakeLists.txt

@@ -203,7 +203,7 @@ IF(CMAKE_COMPILER_IS_GNUCC)
   # For all builds, make sure openjpeg is std99 compliant:
   # SET(CMAKE_C_FLAGS "-Wall -std=c99 ${CMAKE_C_FLAGS}") # FIXME: this setting prevented us from setting a coverage build.
   # Do not use ffast-math for all build, it would produce incorrect results, only set for release:
-  SET(CMAKE_C_FLAGS_RELEASE "-ffast-math ${CMAKE_C_FLAGS_RELEASE}")
+  SET(OPENJPEG_LIBRARY_COMPILE_OPTIONS ${OPENJPEG_LIBRARY_COMPILE_OPTIONS} "$<$<CONFIG:Release>:-ffast-math>")
 ENDIF(CMAKE_COMPILER_IS_GNUCC)
 
 #-----------------------------------------------------------------------------

libopenjpeg/CMakeLists.txt

@@ -39,7 +39,9 @@ IF(UNIX)
   TARGET_LINK_LIBRARIES(${OPENJPEG_LIBRARY_NAME} m)
 ENDIF(UNIX)
 SET_TARGET_PROPERTIES(${OPENJPEG_LIBRARY_NAME} PROPERTIES ${OPENJPEG_LIBRARY_PROPERTIES})
-
+IF(${CMAKE_VERSION} VERSION_GREATER "2.8.11")
+  TARGET_COMPILE_OPTIONS(${OPENJPEG_LIBRARY_NAME} PRIVATE ${OPENJPEG_LIBRARY_COMPILE_OPTIONS})
+ENDIF()
 # Build the JPWL library ?
 IF(BUILD_JPWL)
  ADD_SUBDIRECTORY(jpwl)

libopenjpeg/jpwl/CMakeLists.txt

@@ -26,8 +26,10 @@ ADD_LIBRARY(${OPENJPEG_LIBRARY_NAME}_JPWL ${JPWL_SRCS} ${OPENJPEG_SRCS})
 IF(UNIX)
   TARGET_LINK_LIBRARIES(${OPENJPEG_LIBRARY_NAME}_JPWL m)
 ENDIF(UNIX)
-SET_TARGET_PROPERTIES(${OPENJPEG_LIBRARY_NAME}_JPWL 
-  PROPERTIES ${OPENJPEG_LIBRARY_PROPERTIES})
+SET_TARGET_PROPERTIES(${OPENJPEG_LIBRARY_NAME}_JPWL PROPERTIES ${OPENJPEG_LIBRARY_PROPERTIES})
+IF(${CMAKE_VERSION} VERSION_GREATER "2.8.11")
+  TARGET_COMPILE_OPTIONS(${OPENJPEG_LIBRARY_NAME}_JPWL PRIVATE ${OPENJPEG_LIBRARY_COMPILE_OPTIONS})
+ENDIF()
 
 # Install library
 INSTALL(TARGETS ${OPENJPEG_LIBRARY_NAME}_JPWL