Fix for OS X 10.5 compile error wrt llabs()

GCC < 4.1.0 possibly has a problem w/ choosing an llabs()
unambigiously from stdlib.h and cstdlib

See also http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13943

cmake/OSSpecific.cmake

@@ -1,3 +1,6 @@
+include(CheckCSourceCompiles)
+include(CheckCXXSourceCompiles)
+
 if (${CMAKE_SYSTEM_NAME} MATCHES "FreeBSD")
     # alternate malloc is faster for FreeBSD, but needs more testing
     # need to add way to set this from the command line
@@ -7,6 +10,28 @@ elseif (${CMAKE_SYSTEM_NAME} MATCHES "OpenBSD")
     set(USE_NMALLOC true)
 
 elseif (${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
+    # The following may have a greater scope than just Darwin
+    # (i.e. any platform w/ GCC < 4.1.0), but I've only seen
+    # it on OS X 10.5, which has GCC 4.0.1, so the workaround
+    # will be stuck here for now.
+    #
+    # See also http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13943
+
+    check_cxx_source_compiles("
+        #include <math.h>
+        #include <cstdlib>
+        using namespace std;
+        int main() {
+            llabs(1);
+            return 0;
+        }
+    " darwin_llabs_works)
+
+    if (NOT darwin_llabs_works)
+        # abs() should be used in this case, the long long version should
+        # exist in the __gnu_cxx namespace
+        set(DARWIN_NO_LLABS true)
+    endif ()
 
 elseif (${CMAKE_SYSTEM_NAME} MATCHES "Linux")
     set(HAVE_LINUX true)
@@ -25,7 +50,7 @@ elseif (${CMAKE_SYSTEM_NAME} MATCHES "irix")
 elseif (${CMAKE_SYSTEM_NAME} MATCHES "ultrix")
     list(APPEND CMAKE_C_FLAGS -std1 -g3)
     list(APPEND CMAKE_CXX_FLAGS -std1 -g3)
-    include(CheckCSourceCompiles)
+
     check_c_source_compiles("
         #include <sys/types.h>
         int main() {

config.h.in

@@ -146,3 +146,6 @@
 
 /* Define u_int8_t */
 #define u_int8_t @U_INT8_T@
+
+/* Whether llabs will be ambiguous in stdlib.h and cstdlib headers */
+#cmakedefine DARWIN_NO_LLABS

src/Val.cc

@@ -524,7 +524,11 @@ Val* Val::SizeVal() const
 	{
 	switch ( type->InternalType() ) {
 	case TYPE_INTERNAL_INT:
+#ifdef DARWIN_NO_LLABS
+		return new Val(abs(val.int_val), TYPE_COUNT);
+#else
 		return new Val(llabs(val.int_val), TYPE_COUNT);
+#endif
 
 	case TYPE_INTERNAL_UNSIGNED:
 		return new Val(val.uint_val, TYPE_COUNT);