Set _modulesdir macro for rhel

mp.spec

@@ -16,13 +16,17 @@
 %{!?__global_ldflags: %global __global_ldflags -Wl,-z,relro}
 %endif
 
+%if 0%{?rhel}
+%{!?_modulesdir: %global _modulesdir %{_datadir}/Modules/modulefiles}
+%endif
+
 %global  commit      1f39801af085656e4bf72250356a3a70d5d98e73
 %global  date        20161124
 %global  shortcommit %(c=%{commit}; echo ${c:0:7})
 
 Name: mp
 Version: 3.1.0
-Release: 21.%{date}git%{shortcommit}%{?dist}
+Release: 22.%{date}git%{shortcommit}%{?dist}
 License: MIT and BSD
 Summary: An open-source library for mathematical programming
 URL: https://github.com/ampl/mp
@@ -274,6 +278,9 @@ ctest --force-new-ctest-process --parallel %{?_smp_mflags} -I 4,15,,1,17,28
 %{_includedir}/mp
 
 %changelog
+* Tue May 07 2019 Antonio Trande <sagitter@fedoraproject.org.com> - 3.1.0-22.20160810git1f39801
+- Set _modulesdir macro for rhel
+
 * Tue May 07 2019 Antonio Trande <sagitter@fedoraproject.org.com> - 3.1.0-21.20160810git1f39801
 - Some improvements