Backport of (part of) bug #11760838 to 5.5.

Enabled the ABI check to run on MacOSX.

cmake/abi_check.cmake

@@ -19,8 +19,16 @@
 # plugin_audit.h and plugin_ftparser.h.
 #
 # We use gcc specific preprocessing command and sed/diff, so it will 
-# only be run  on Unix and only if gcc is used.
-IF(CMAKE_COMPILER_IS_GNUCC AND CMAKE_SYSTEM_NAME MATCHES "Linux")
+# only be run  on Unix and only if gcc is used. On some Unixes,
+# (Solaris) sed or diff might act differently from GNU, so we run only 
+# on systems we can trust.
+IF(APPLE OR CMAKE_SYSTEM_NAME MATCHES "Linux")
+ SET(RUN_ABI_CHECK 1)
+ELSE()
+ SET(RUN_ABI_CHECK 0)
+ENDIF()
+
+IF(CMAKE_COMPILER_IS_GNUCC AND RUN_ABI_CHECK)
   IF(CMAKE_C_COMPILER MATCHES "ccache$")
     SET(COMPILER ${CMAKE_C_COMPILER_ARG1})
     STRING(REGEX REPLACE "^ " "" COMPILER ${COMPILER})