Move docs generation from prep section to build section

wxGTK3.spec

@@ -182,15 +182,6 @@ sed -i -e 's|aclocal)|aclocal/wxwin3.m4)|' Makefile.in
 sed -i -e 's|wxstd.mo|wxstd3.mo|' Makefile.in
 sed -i -e 's|wxmsw.mo|wxmsw3.mo|' Makefile.in
 
-#Docs
-%if 0%{?builddocs}
-export WX_SKIP_DOXYGEN_VERSION_CHECK=1
-docs/doxygen/regen.sh html
-mv docs/doxygen/out/html .
-%else
-mv %{srcname}-%{version} html
-%endif
-
 # fix plugin dir for 64-bit
 sed -i -e 's|/usr/lib\b|%{_libdir}|' wx-config.in configure
 sed -i -e 's|/lib|/%{_lib}|' src/unix/stdpaths.cpp
@@ -228,6 +219,14 @@ popd
 
 %make_build
 
+#Docs
+%if 0%{?builddocs}
+WX_SKIP_DOXYGEN_VERSION_CHECK=1 docs/doxygen/regen.sh html
+mv docs/doxygen/out/html .
+%else
+mv %{srcname}-%{version} html
+%endif
+
 pushd docs/doxygen
 WX_SKIP_DOXYGEN_VERSION_CHECK=1 ./regen.sh xml
 popd