cmake: Rename installhdrs to install-llvm-headers and fix the dependencies

The installhdrs target was inconsistently named and would behave
differently depending on whether or not you ran a build first. This
renames it to install-llvm-headers to match other target names and
adds a dependency on intrinsics_gen so that it will always install the
same set of things.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@285035 91177308-0d34-0410-b5e6-96231b3b80d8

CMakeLists.txt

@@ -890,9 +890,13 @@ if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY)
     PATTERN ".svn" EXCLUDE
     )
 
+  # Installing the headers needs to depend on generating any public
+  # tablegen'd headers.
+  add_custom_target(llvm-headers DEPENDS intrinsics_gen)
+
   if (NOT CMAKE_CONFIGURATION_TYPES)
-    add_custom_target(installhdrs
-                      DEPENDS ${name}
+    add_custom_target(install-llvm-headers
+                      DEPENDS llvm-headers
                       COMMAND "${CMAKE_COMMAND}"
                               -DCMAKE_INSTALL_COMPONENT=llvm-headers
                               -P "${CMAKE_BINARY_DIR}/cmake_install.cmake")