Enable C++11 mode and re-enable C++ exception handling.

Makefile

@@ -24,6 +24,7 @@ default : all
 
 PREFIX ?= /usr/local
 UNIX_ADAPTER_EXE ?= console.exe
+MINGW_ENABLE_CXX11_FLAG ?= -std=c++11
 
 # Include config.mk but complain if it hasn't been created yet.
 ifeq "$(wildcard config.mk)" ""
@@ -45,9 +46,8 @@ UNIX_CXXFLAGS += \
 
 MINGW_CXXFLAGS += \
 	$(COMMON_CXXFLAGS) \
-	-fno-exceptions \
-	-fno-rtti \
-	-O2
+	-O2 \
+	$(MINGW_ENABLE_CXX11_FLAG)
 
 MINGW_LDFLAGS += -static -static-libgcc -static-libstdc++
 UNIX_LDFLAGS += $(UNIX_LDFLAGS_STATIC)

configure

@@ -148,6 +148,12 @@ echo MINGW_CXX=$MINGW_CXX >> config.mk
 
 if test $IS_MSYS1 = 1; then
     echo UNIX_CXXFLAGS += -DWINPTY_TARGET_MSYS1 >> config.mk
+    # The MSYS1 MinGW compiler has a bug that prevents inclusion of algorithm
+    # and math.h in normal C++11 mode.  The workaround is to enable the gnu++11
+    # mode instead.  The bug was fixed on 2015-07-31, but as of 2016-02-26, the
+    # fix apparently hasn't been released.  See
+    # http://ehc.ac/p/mingw/bugs/2250/.
+    echo MINGW_ENABLE_CXX11_FLAG = -std=gnu++11 >> config.mk
 fi
 
 # Figure out how to embed build info (e.g. git commit) into the binary.