Issue #27076: Doc, comment and tests spelling fixes

Most fixes to Doc/ and Lib/ directories by Ville Skyttä.

msvc9compiler.py

@@ -51,7 +51,7 @@ else:
 
 # A map keyed by get_platform() return values to values accepted by
 # 'vcvarsall.bat'.  Note a cross-compile may combine these (eg, 'x86_amd64' is
-# the param to cross-compile on x86 targetting amd64.)
+# the param to cross-compile on x86 targeting amd64.)
 PLAT_TO_VCVARS = {
     'win32' : 'x86',
     'win-amd64' : 'amd64',

tests/test_unixccompiler.py

@@ -127,7 +127,7 @@ class UnixCCompilerTestCase(unittest.TestCase):
         self.assertEqual(self.cc.linker_so[0], 'my_cc')
 
     @unittest.skipUnless(sys.platform == 'darwin', 'test only relevant for OS X')
-    def test_osx_explict_ldshared(self):
+    def test_osx_explicit_ldshared(self):
         # Issue #18080:
         # ensure that setting CC env variable does not change
         #   explicit LDSHARED setting for linker