SCons: Set explicit standards to C++98 and C11

Godot 1.0 was developed at a time where compilers defaulted to C++98.

Also disable `-Wall` on debug builds, there are now hundreds of warnings
from newer compilers that would need to be fixed.

This would best be done by adding a new `warnings` SCons option, which would
also affect non-debug builds, but I have no intention to fix warnings in the
1.0 branch, the goal here is just to get it to compile for archival and game
preservation.

platform/javascript/detect.py

@@ -70,7 +70,7 @@ def configure(env):
 		env.Append(CCFLAGS=['-O2','-DDEBUG_ENABLED'])
 
 	elif (env["target"]=="debug"):
-		env.Append(CCFLAGS=['-D_DEBUG', '-Wall', '-O2', '-DDEBUG_ENABLED'])
+		env.Append(CCFLAGS=['-D_DEBUG', '-O2', '-DDEBUG_ENABLED'])
 		env.Append(CPPFLAGS=['-DDEBUG_MEMORY_ALLOC'])
 
 	env.Append(CPPFLAGS=["-fno-exceptions",'-DNO_SAFE_CAST','-fno-rtti'])