Remove unneeded compile options.

In light of issue official-stockfish#1232, a test was performed about the value of '-fno-exceptions' and a second one of the combination '-fno-exceptions -fno-rtti'. It turns out these options are can be removed without introducing slowdown.

STC for removing '-fno-exceptions'
LLR: 2.94 (-2.94,2.94) [-3.00,1.00]
Total: 13678 W: 2572 L: 2439 D: 8667

STC for removing '-fno-exceptions -fno-rtti' (current patch)
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 32557 W: 6074 L: 5973 D: 20510

No functional change.

src/Makefile

@@ -141,7 +141,7 @@ endif
 
 ### 3.1 Selecting compiler (default = gcc)
 
-CXXFLAGS += -Wall -Wcast-qual -fno-exceptions -fno-rtti -std=c++11 $(EXTRACXXFLAGS)
+CXXFLAGS += -Wall -Wcast-qual -std=c++11 $(EXTRACXXFLAGS)
 DEPENDFLAGS += -std=c++11
 LDFLAGS += $(EXTRALDFLAGS)