macros.cmake: introduce %_cmake_shared_libs macro

... makes it easier to override or disable.

cmake.spec

@@ -64,7 +64,7 @@
 
 Name:           %{orig_name}%{?name_suffix}
 Version:        %{major_version}.%{minor_version}.1
-Release:        1%{?relsuf}%{?dist}
+Release:        2%{?relsuf}%{?dist}
 Summary:        Cross-platform make system
 
 # most sources are BSD
@@ -500,6 +500,9 @@ update-mime-database %{?fedora:-n} %{_datadir}/mime &> /dev/null || :
 
 
 %changelog
+* Sat Dec 08 2018 Rex Dieter <rdieter@fedoraproject.org> - 3.13.1-2
+- macros.cmake: introduce %%_cmake_shared_libs macro
+
 * Wed Nov 28 2018 Rex Dieter <rdieter@fedoraproject.org> - 3.13.1-1
 - 3.13.1
 

macros.cmake

@@ -2,6 +2,7 @@
 # Macros for cmake
 #
 %_cmake_lib_suffix64 -DLIB_SUFFIX=64
+%_cmake_shared_libs -DBUILD_SHARED_LIBS:BOOL=ON
 %_cmake_skip_rpath -DCMAKE_SKIP_RPATH:BOOL=ON
 %_cmake_version @@CMAKE_VERSION@@
 %__cmake /usr/bin/cmake
@@ -31,6 +32,6 @@
 %if "%{?_lib}" == "lib64" \
         %{?_cmake_lib_suffix64} \\\
 %endif \
-        -DBUILD_SHARED_LIBS:BOOL=ON
+	%{?_cmake_shared_libs}
 
 %cmake@@CMAKE_MAJOR_VERSION@@ %cmake