Move ldc internal headers to /usr/lib/ldc to avoid conflicting with gdc

This matches with what Debian does, and is what the gcc maintainers
suggest.

The idea is to have ldc internal headers (those that cannot be used by
gdc and cause conflicts) in /usr/lib/ldc/%{_target_platform}/include/d/,
and keep library header files (those that both ldc and gdc can use) in
/usr/include/d/.

https://bugzilla.redhat.com/show_bug.cgi?id=1781685

ldc-include-path.patch

@@ -0,0 +1,19 @@
+Description: Fix ldc.conf to search in right paths
+
+ ldc (1:1.1.0-2) unstable; urgency=medium
+ .
+   * Multiarch enable
+   * Install includes separately to avoid clash with gdc (Closes: #827211)
+Author: Konstantinos Margaritis <markos@debian.org>
+Bug-Debian: https://bugs.debian.org/827211
+
+--- a/ldc2_install.conf.in
++++ b/ldc2_install.conf.in
+@@ -23,6 +23,7 @@
+     // default switches appended after all explicit command-line switches
+     post-switches = [
+         "-I@INCLUDE_INSTALL_DIR@",
++        "-I/usr/include/d",
+     ];
+     // default directories to be searched for libraries when linking
+     lib-dirs = [

ldc.spec

@@ -36,6 +36,9 @@ Source1:        https://github.com/ldc-developers/ldc/releases/download/v%{boots
 %endif
 Source3:        macros.%{name}
 
+# Make sure /usr/include/d is in the include search path
+Patch0:         ldc-include-path.patch
+
 ExclusiveArch:  %{ldc_arches}
 
 %if ! 0%{?bootstrap_stage1}
@@ -158,7 +161,7 @@ popd
 %endif
 
 %cmake -DMULTILIB:BOOL=OFF \
-       -DINCLUDE_INSTALL_DIR:PATH=%{_includedir}/d           \
+       -DINCLUDE_INSTALL_DIR:PATH=%{_prefix}/lib/ldc/%{_target_platform}/include/d \
        -DLLVM_CONFIG:PATH=llvm-config-%{?llvm_version:%{llvm_version}-}%{__isa_bits} \
 %if 0%{?bootstrap_stage2}
        -DD_COMPILER:PATH=`pwd`/build-bootstrap2/bin/ldmd2 \
@@ -195,12 +198,15 @@ install -m0644 phobos.d.tags %{buildroot}/%{_datadir}/geany/tags/
 %{_bindir}/ldc-profdata
 %{_bindir}/ldc-prune-cache
 %{_rpmconfigdir}/macros.d/macros.ldc
-%dir %{_includedir}/d
-%{_includedir}/d/core
-%{_includedir}/d/etc
-%{_includedir}/d/ldc
-%{_includedir}/d/object.d
-%{_includedir}/d/std
+%dir %{_prefix}/lib/ldc
+%dir %{_prefix}/lib/ldc/%{_target_platform}
+%dir %{_prefix}/lib/ldc/%{_target_platform}/include
+%dir %{_prefix}/lib/ldc/%{_target_platform}/include/d
+%{_prefix}/lib/ldc/%{_target_platform}/include/d/core
+%{_prefix}/lib/ldc/%{_target_platform}/include/d/etc
+%{_prefix}/lib/ldc/%{_target_platform}/include/d/ldc
+%{_prefix}/lib/ldc/%{_target_platform}/include/d/object.d
+%{_prefix}/lib/ldc/%{_target_platform}/include/d/std
 %{_libdir}/libdruntime-ldc-debug-shared.so
 %{_libdir}/libdruntime-ldc-shared.so
 %{_libdir}/libldc-jit-rt.a
@@ -238,6 +244,7 @@ install -m0644 phobos.d.tags %{buildroot}/%{_datadir}/geany/tags/
 * Fri Aug 21 2020 Kalev Lember <klember@redhat.com> - 1:1.23.0-1
 - Update to 1.23.0
 - Merge -devel subpackages into the main ldc package
+- Move ldc internal headers to /usr/lib/ldc to avoid conflicting with gdc (#1781685)
 
 * Fri Aug 21 2020 Kalev Lember <klember@redhat.com> - 1:1.20.1-5
 - Explicitly build against llvm10 compat package