gdal: Patch to support hdf linked against libtirpc (#15995)

If hdf was built with +libtirpc, we need to add -ltirpc to our link
flags.

var/spack/repos/builtin/packages/gdal/package.py

@@ -172,6 +172,7 @@ def setup_build_environment(self, env):
     # https://trac.osgeo.org/gdal/wiki/BuildHints
     def configure_args(self):
         spec = self.spec
+        libs = []
 
         # Required dependencies
         args = [
@@ -294,6 +295,9 @@ def configure_args(self):
         # https://trac.osgeo.org/gdal/wiki/HDF
         if '+hdf4' in spec:
             args.append('--with-hdf4={0}'.format(spec['hdf'].prefix))
+            hdf4 = self.spec['hdf']
+            if '+libtirpc' in hdf4:
+                libs.append('-ltirpc')
         else:
             args.append('--with-hdf4=no')
 
@@ -480,6 +484,9 @@ def configure_args(self):
                 '--with-pdfium=no',
             ])
 
+        if libs:
+            args.append('LIBS=' + ' '.join(libs))
+
         return args
 
     @run_after('install')