CMake sanitize leading define flag (#2130)

TYPE: bug fix

KEYWORDS: compilation, cmake

SOURCE: internal

DESCRIPTION OF CHANGES:
Problem:
With the addition of #2088, `ARCH_LOCAL` from the stanza is now being
fed into compilation with potential `-D` defines. On versions of CMake
<3.26 leading `-D` on defines is not removed from certain function calls
like `add_compile_definitions()`. This will pass the configuration stage
but will fail to compile when using the defined minimum CMake version of
the project.

Solution:
To simplify the logic, all defines fed into the `wrf_config.cmake` file
for the configuration step will be sanitized of leading `-D`. This
follows the original design intent where stanza sanitization happens
before being fed into CMake, thus allowing the CMake code to focus on
configuration of options rather than translation of stanza into usable
values.


TESTS CONDUCTED: 
1. Tested configuration and compilation on CMake version v3.20.6

RELEASE NOTE: 
Remove leading -D on defines during stanza reading to allow older 
versions of CMake to configure properly.

arch/configure_reader.py

@@ -19,6 +19,7 @@
 referenceVar  = re.compile( r"[$]([(])?(\w+)(?(1)[)])", re.I )
 compileObject = re.compile( r"(\W|^)-c(\W|$)" )
 configureRepl = re.compile( r"(\W|^)CONFIGURE_\w+(\W|$)" )
+defineRepl    = re.compile( r"-D([^ ]+)" )
 
 class Stanza():
 
@@ -164,6 +165,7 @@ def sanitize( self ) :
     for keyToSan in self.kvPairs_.keys() :
       self.kvPairs_[ keyToSan ] = configureRepl.sub( r"\1\2", self.kvPairs_[ keyToSan ] ).strip()
       self.kvPairs_[ keyToSan ] = compileObject.sub( r"\1\2", self.kvPairs_[ keyToSan ] ).strip()
+      self.kvPairs_[ keyToSan ] =    defineRepl.sub( r"\1",   self.kvPairs_[ keyToSan ] ).strip()
 
 
     # Now fix certain ones that are mixing programs with flags all mashed into one option