Remove -std=c++11 since yaml-cpp is not used anymore

Author: abzrg

Makefile

@@ -48,9 +48,6 @@ CFLAGS  = -Wall -O3 -fopenmp $(INCLUDES)
 CFLAGS += -DARCH="Linux" -DSPOOLES -DARPACK -DMATRIXSTORAGE -DUSE_MT
 CFLAGS += -Wno-implicit-function-declaration -Wno-incompatible-pointer-types
 
-# yaml-cpp 0.6.0+ requires C++11
-CXXFLAGS += -std=c++11
-
 # OS-specific options
 UNAME_S := $(shell uname -s)
 ifeq ($(UNAME_S),Darwin)