"Detect" macports vs homebrew

Just looks for the /opt v /usr dir, probably not very fool proof
Prefers home-brew in case of conflict in detection.

src/makefile.osx

@@ -9,7 +9,16 @@
 
 STATIC=yes
 CXX=c++
-DEPSDIR=/usr/local
+
+MACPORTSDIR=$(wildcard /opt/local)
+HOMEBREWDIR=$(wildcard /usr/local)
+
+ifneq ($(HOMEBREWDIR),)
+    DEPSDIR=$(HOMEBREWDIR)
+else
+    DEPSDIR=$(MACPORTSDIR)
+endif
+
 
 INCLUDEPATHS= \
  -I"$(CURDIR)" \
@@ -56,7 +65,7 @@ LIBS += \
 TESTDEFS += -DBOOST_TEST_DYN_LINK
 endif
 
-DEFS=-DMAC_OSX -DMSG_NOSIGNAL=0 -DBOOST_SPIRIT_THREADSAFE
+DEFS=-DMAC_OSX -DBOOST_SPIRIT_THREADSAFE
 
 ifdef RELEASE
 # Compile for maximum compatibility and smallest size.