Fix FTBFS (#1987636)

lensfun.spec

@@ -6,7 +6,7 @@
 Name:    lensfun
 Version: 0.3.2
 Summary: Library to rectify defects introduced by photographic lenses
-Release: 33%{?dist}
+Release: 34%{?dist}
 
 License: LGPLv3 and CC-BY-SA
 URL: https://lensfun.github.io/
@@ -111,7 +111,7 @@ sed -i.shbang \
 
 %cmake_build
 
-make doc -C %{_target_platform}
+make doc -C %{_vendor}-%{_target_os}-build
 
 
 %install
@@ -167,6 +167,9 @@ export CTEST_OUTPUT_ON_FAILURE=1
 
 
 %changelog
+* Tue Aug 03 2021 Graham White <graham_alton@hotmail.com> - 0.3.2-34
+- Fix FTBFS (#1987636)
+
 * Thu Jul 22 2021 Fedora Release Engineering <releng@fedoraproject.org> - 0.3.2-33
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_35_Mass_Rebuild