Extended Description

(After #40944 and a separate private query, it really seems this should
have had a release note. Tom please DTRT with this, rephrase as needed.)

Three of the IR library methods related to debugging information for
functions and methods have changed their prototypes:

DIBuilder::createMethod
DIBuilder::createFunction
DIBuilder::createTempFunctionFwdDecl

In all cases, several individual parameters were removed, and replaced
by a single 'SPFlags' (subprogram flags) parameter. The individual
parameters are: 'isLocalToUnit'; 'isDefinition'; 'isOptimized'; and
for 'createMethod', 'Virtuality'. The new 'SPFlags' parameter has a
default value equivalent to passing 'false' for the three 'bool'
parameters, and zero (non-virtual) to the 'Virtuality' parameter. For
any old-style API call that passed 'true' or a non-zero virtuality to
these methods, you will need to substitute the correct 'SPFlags' value.
The helper method 'DISubprogram::toSPFlags()' might be useful in making
this conversion.