Get build flags from environment, using extra ATLAS_CFLAGS and ATLAS_LIBS for ATLAS library.

diff -r 6c9ab70d2386 build/linux/Makefile.linux32
--- a/build/linux/Makefile.linux32	Sun Sep 28 10:59:50 2014 +0100
+++ b/build/linux/Makefile.linux32	Sat Nov 01 14:25:19 2014 +0100
@@ -1,10 +1,11 @@
+ATLAS_LIBS ?= -L/usr/lib/sse2/atlas -L/usr/lib/atlas/sse -llapack -lblas
 
-CFLAGS := -DNDEBUG -O3 -fno-exceptions -fPIC -ffast-math -msse -mfpmath=sse -ftree-vectorize -fomit-frame-pointer -DUSE_PTHREADS
+CFLAGS := -DNDEBUG -O3 -fno-exceptions -fPIC -ffast-math -msse -mfpmath=sse -ftree-vectorize -fomit-frame-pointer -DUSE_PTHREADS $(ATLAS_CFLAGS) $(CFLAGS)
 #CFLAGS	:= -g -Wall
 
 CXXFLAGS := $(CFLAGS)
 
-LDFLAGS	 := -Wl,-Bstatic -lqm-dsp -lvamp-sdk -L/usr/lib/sse2/atlas -L/usr/lib/atlas/sse -llapack -lblas -Wl,-Bdynamic -lpthread -Wl,-z,defs -Wl,--version-script=vamp-plugin.map
+LDFLAGS	 := -Wl,-Bstatic -lqm-dsp -lvamp-sdk -Wl,-Bdynamic -lpthread -Wl,-z,defs -Wl,--version-script=vamp-plugin.map $(ATLAS_LIBS) $(LDFLAGS)
 
 PLUGIN_EXT   := .so
 
diff -r 6c9ab70d2386 build/linux/Makefile.linux64
--- a/build/linux/Makefile.linux64	Sun Sep 28 10:59:50 2014 +0100
+++ b/build/linux/Makefile.linux64	Sat Nov 01 14:25:19 2014 +0100
@@ -1,9 +1,10 @@
+ATLAS_LIBS ?= -Lbuild/linux/amd64 -L/usr/lib/sse2/atlas -L/usr/lib/atlas/sse -llapack -lcblas -lf77blas -latlas
 
-CFLAGS += -DNDEBUG -O3 -fno-exceptions -fPIC -ffast-math -msse -msse2 -mfpmath=sse -ftree-vectorize -DUSE_PTHREADS
+CFLAGS := -DNDEBUG -O3 -fno-exceptions -fPIC -ffast-math -msse -msse2 -mfpmath=sse -ftree-vectorize -DUSE_PTHREADS $(ATLAS_CFLAGS) $(CFLAGS)
 
-CXXFLAGS += $(CFLAGS)
+CXXFLAGS := $(CFLAGS)
 
-LDFLAGS	 += -shared -Lbuild/linux/amd64 -Wl,-Bstatic -lqm-dsp -lvamp-sdk -L/usr/lib/sse2/atlas -L/usr/lib/atlas/sse -llapack -lcblas -lf77blas -latlas -Wl,-z,defs -Wl,-Bdynamic -lpthread -Wl,--version-script=vamp-plugin.map
+LDFLAGS	 := -shared -lqm-dsp -lvamp-sdk -Wl,-z,defs -Wl,-Bdynamic -lpthread -Wl,--version-script=vamp-plugin.map $(ATLAS_LIBS) $(LDFLAGS)
 
 PLUGIN_EXT   := .so