A few win fixes.

mesonbuild/backend/ninjabackend.py

@@ -1725,8 +1725,10 @@ rule FORTRAN_DEP_HACK
                 pass
             try:
                 os.symlink(basename, aliasfile)
+            except NotImplementedError:
+                mlog.debug("Library versioning disabled because symlinks are not supported.")
             except OSError:
-                mlog.debug("Library versioning disabled because we do not have symlink creation privileges")
+                mlog.debug("Library versioning disabled because we do not have symlink creation privileges.")
 
     def generate_gcov_clean(self, outfile):
             gcno_elem = NinjaBuildElement(self.all_outputs, 'clean-gcno', 'CUSTOM_COMMAND', 'PHONY')

mesonbuild/coredata.py

@@ -61,8 +61,10 @@ class UserStringOption(UserOption):
     def validate(self, value):
         if not isinstance(value, str):
             raise MesonException('Value "%s" for string option "%s" is not a string.' % (str(newvalue), self.name))
-        if self.name == 'prefix' and not os.path.isabs(value):
-            raise MesonException('Prefix option value \'{0}\' must be an absolute path.'.format(value))
+        if self.name == 'prefix':
+            if not os.path.isabs(value):
+                if len(value) >= 2 and value[1] != ':':
+                    raise MesonException('Prefix option value \'{0}\' must be an absolute path.'.format(value))
         if self.name in ('libdir', 'bindir', 'includedir', 'datadir', 'mandir', 'localedir') \
             and os.path.isabs(value):
             raise MesonException('Option %s must not be an absolute path.' % self.name)