[llvm] [flang][rt] Add install target for header files (PR #165610)

[Valentin Clement バレンタイン クレメン via llvm-commits]

https://github.com/clementval created https://github.com/llvm/llvm-project/pull/165610

Header files of the runtime were not installed. This patch adds an install target to install the headers under the include directory similar to the flang header files. 

>From 6be184e109ac48373d076cdf92c01ab838a1924d Mon Sep 17 00:00:00 2001
From: Valentin Clement <clementval at gmail.com>
Date: Wed, 29 Oct 2025 11:39:08 -0700
Subject: [PATCH] [flang][rt] Add install target for header files

---
 flang-rt/CMakeLists.txt | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/flang-rt/CMakeLists.txt b/flang-rt/CMakeLists.txt
index cad39d0c71016..50b8e834776fb 100644
--- a/flang-rt/CMakeLists.txt
+++ b/flang-rt/CMakeLists.txt
@@ -330,3 +330,19 @@ if (FLANG_RT_INCLUDE_TESTS)
 else ()
   add_custom_target(check-flang-rt)
 endif()
+
+###################
+# Install headers #
+###################
+
+if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY)
+  add_llvm_install_targets(install-flang-rt-headers COMPONENT flang-rt-headers)
+
+  install(DIRECTORY include/flang-rt/runtime
+    DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/flang-rt"
+    COMPONENT flang-rt-headers
+    FILES_MATCHING
+    PATTERN "*.h"
+    PATTERN ".git" EXCLUDE
+    PATTERN "CMakeFiles" EXCLUDE)
+endif()