sys-cluster/mpich2: Restore missing conf opts

* Commit 4c2a599 errantly removed use of a temporary variable when
  converting the calling method to use bash.

Closes: https://bugs.gentoo.org/814548
Closes: #22592
Signed-off-by: Sam James <sam@gentoo.org>

sys-cluster/mpich2/mpich2-1.5.ebuild → sys-cluster/mpich2/mpich2-1.5-r1.ebuild

@@ -89,7 +89,7 @@ src_configure() {
 	c="${c} --docdir=${EPREFIX}/usr/share/doc/${PF}"
 
 	# Forcing Bash as there's quite a few bashisms in the build system
-	CONFIG_SHELL="${BROOT}/bin/bash" econf \
+	CONFIG_SHELL="${BROOT}/bin/bash" econf ${c} \
 		--with-pm=hydra \
 		--disable-mpe \
 		--disable-fast \