This passes all CFLAGS to the buildsystem, not only -std=c99.

Signed-off-by: Thomas Gstädtner <thomas@???>
---
 src/filter/curves/CMakeLists.txt              |    2 +-
 src/filter/levels/CMakeLists.txt              |    2 +-
 src/filter/three_point_balance/CMakeLists.txt |    2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/filter/curves/CMakeLists.txt b/src/filter/curves/CMakeLists.txt
index 6a71f7e..51183bf 100644
--- a/src/filter/curves/CMakeLists.txt
+++ b/src/filter/curves/CMakeLists.txt
@@ -1,6 +1,6 @@
 # Set C99 flag for gcc
 if (CMAKE_COMPILER_IS_GNUCC)
-    set(CMAKE_C_FLAGS "-std=c99")
+  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=c99")
 endif (CMAKE_COMPILER_IS_GNUCC)

 set (SOURCES curves.c)
diff --git a/src/filter/levels/CMakeLists.txt b/src/filter/levels/CMakeLists.txt
index ef66de8..7b93c15 100644
--- a/src/filter/levels/CMakeLists.txt
+++ b/src/filter/levels/CMakeLists.txt
@@ -1,6 +1,6 @@
 # Set C99 flag for gcc
 if (CMAKE_COMPILER_IS_GNUCC)
-    set(CMAKE_C_FLAGS "-std=c99")
+  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=c99")
 endif (CMAKE_COMPILER_IS_GNUCC)

 set (SOURCES levels.c)
diff --git a/src/filter/three_point_balance/CMakeLists.txt b/src/filter/three_point_balance/CMakeLists.txt
index 7a3b35f..bacf2ef 100644
--- a/src/filter/three_point_balance/CMakeLists.txt
+++ b/src/filter/three_point_balance/CMakeLists.txt
@@ -1,6 +1,6 @@
 # Set C99 flag for gcc
 if (CMAKE_COMPILER_IS_GNUCC)
-    set(CMAKE_C_FLAGS "-std=c99")
+  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=c99")
 endif (CMAKE_COMPILER_IS_GNUCC)

set (SOURCES three_point_balance.c)
--
1.7.8.6