rpm: avoid redefining %dist for Amazon Linux

rpm/SPECS/nginx-module.spec.in

diff --git a/rpm/SPECS/nginx-module.spec.in b/rpm/SPECS/nginx-module.spec.in
index e64074e..43e2f8e 100644
--- a/rpm/SPECS/nginx-module.spec.in
+++ b/rpm/SPECS/nginx-module.spec.in
@@ -13,7 +13,7 @@
 %define _debugsource_template %{nil}
 %endif
 
-%if 0%{?rhel} == 7
+%if (0%{?rhel} == 7) && (0%{?amzn} == 0)
 %define epoch 1
 Epoch: %{epoch}
 %define dist .el7

rpm/SPECS/nginx-plus-module.spec.in

diff --git a/rpm/SPECS/nginx-plus-module.spec.in b/rpm/SPECS/nginx-plus-module.spec.in
index b6157a1..d1acb23 100644
--- a/rpm/SPECS/nginx-plus-module.spec.in
+++ b/rpm/SPECS/nginx-plus-module.spec.in
@@ -19,7 +19,7 @@
 %define _debugsource_template %{nil}
 %endif
 
-%if 0%{?rhel} == 7
+%if (0%{?rhel} == 7) && (0%{?amzn} == 0)
 %define dist .el7
 %endif