Fix apr detection

ConfigureChecks.cmake

@@ -118,14 +118,20 @@ IF (UNIX)
     MESSAGE(SEND_ERROR "Error: no apu-config found")
   endif(NOT APU_CONFIG)
 
-  EXEC_PROGRAM(${APR_CONFIG} ARGS "--includedir" OUTPUT_VARIABLE APR_INCLUDE_DIR)
-  EXEC_PROGRAM(${APU_CONFIG} ARGS "--includedir" OUTPUT_VARIABLE APU_INCLUDE_DIR)
-
-  EXEC_PROGRAM(${APR_CONFIG} ARGS "--cppflags" OUTPUT_VARIABLE APR_CPP_FLAGS)
-  EXEC_PROGRAM(${APU_CONFIG} ARGS "--cppflags" OUTPUT_VARIABLE APU_CPP_FLAGS)
-
-  EXEC_PROGRAM(${APR_CONFIG} ARGS "--ldflags --libs --link-ld" OUTPUT_VARIABLE APR_EXTRA_LIBFLAGS)
-  EXEC_PROGRAM(${APU_CONFIG} ARGS "--ldflags --libs --link-ld" OUTPUT_VARIABLE APU_EXTRA_LIBFLAGS)
+  EXEC_PROGRAM(${APR_CONFIG} ARGS "--includedir" OUTPUT_VARIABLE APR_INCLUDE_DIR_INT)
+  EXEC_PROGRAM(${APU_CONFIG} ARGS "--includedir" OUTPUT_VARIABLE APU_INCLUDE_DIR_INT)
+  SET(APR_INCLUDE_DIR "${APR_INCLUDE_DIR_INT}" CACHE INTERNAL "")
+  SET(APU_INCLUDE_DIR "${APU_INCLUDE_DIR_INT}" CACHE INTERNAL "")
+
+  EXEC_PROGRAM(${APR_CONFIG} ARGS "--cppflags" OUTPUT_VARIABLE APR_CPP_FLAGS_INT)
+  EXEC_PROGRAM(${APU_CONFIG} ARGS "--includes" OUTPUT_VARIABLE APU_CPP_FLAGS_INT)
+  SET(APR_CPP_FLAGS "${APR_CPP_FLAGS_INT}" CACHE INTERNAL "")
+  SET(APU_CPP_FLAGS "${APU_CPP_FLAGS_INT}" CACHE INTERNAL "")
+
+  EXEC_PROGRAM(${APR_CONFIG} ARGS "--ldflags --libs --link-ld" OUTPUT_VARIABLE APR_EXTRA_LIBFLAGS_INT)
+  EXEC_PROGRAM(${APU_CONFIG} ARGS "--ldflags --libs --link-ld" OUTPUT_VARIABLE APU_EXTRA_LIBFLAGS_INT)
+  SET(APR_EXTRA_LIBFLAGS "${APR_EXTRA_LIBFLAGS_INT}" CACHE INTERNAL "")
+  SET(APU_EXTRA_LIBFLAGS "${APU_EXTRA_LIBFLAGS_INT}" CACHE INTERNAL "")
 
   CHECK_INCLUDE_FILES(execinfo.h HAS_BACKTRACE_H)