Turn off exceptions in C++

We don't use them in our code and Qt doesn't throw either, so save a
few bytes and maybe a few setjump() calls on Windows.

Signed-off-by: Thiago Macieira <thiago@macieira.org>

subsurface-configure.pri

@@ -11,6 +11,10 @@
 # Don't turn warnings on (but don't suppress them either)
 CONFIG -= warn_on warn_off
 
+# Turn exceptions off
+!win32-msvc*: QMAKE_CXXFLAGS += -fno-exceptions
+CONFIG += exceptions_off
+
 # Check if we have pkg-config
 equals($$QMAKE_HOST.os, "Windows"):NUL=NUL
 else:NUL=/dev/null