Set R(UN)PATH to fix running

```
[user@rosa2019 tmp]$ /opt/llvm11/bin/clang c.c
/opt/llvm11/bin/clang: error while loading shared libraries: libclang-cpp.so.11: cannot open shared object file: No such file or directory
[user@rosa2019 tmp]$ LD_LIBRARY_PATH=/opt/llvm11/lib64 /opt/llvm11/bin/clang c.c
[user@rosa2019 tmp]$ ./a.out
[user@rosa2019 tmp]$
```

llvm11.spec

@@ -12,6 +12,9 @@
 %define debugcflags %{nil}
 %define debug_package %{nil}
 
+%global optflags %{optflags} -fno-strict-aliasing
+%global ldflags %{ldflags} -Wl,-rpath,%{_libdir}
+
 # clang header paths are hard-coded at compile time
 # and need adjustment whenever there's a new GCC version
 %define gcc_version %(gcc -dumpversion)
@@ -25,7 +28,7 @@ Summary:	LLVM and Clang in %{_prefix}
 # llvm11
 Name:		llvm%{maj_ver}
 Version:	%{maj_ver}.0.1
-Release:	1
+Release:	2
 License:	NCSA
 Group:		Development/Other
 Url:		http://llvm.org
@@ -49,6 +52,8 @@ BuildRequires:	libstdc++-devel
 BuildRequires:	libtool
 BuildRequires:	pkgconfig(libffi)
 BuildRequires:	pkgconfig(libtirpc)
+# patchelf is for %%check
+BuildRequires:	patchelf
 BuildRequires:	sed
 BuildRequires:	tcl
 BuildRequires:	zip
@@ -150,7 +155,6 @@ cd tools/clang
 cd -
 
 %build
-%global optflags %{optflags} -fno-strict-aliasing
 # Build with gcc/g++, not clang if it happens to be installed
 export CC=gcc
 export CXX=g++
@@ -227,3 +231,6 @@ cp -a build/%{_lib}/LLVMHello.so %{buildroot}%{_libdir}
 
 # Versionize shebangs python
 sed '1 s,^.*$,#!%{__python3},' -i %{buildroot}%{_bindir}/{hmaptool,scan-view}
+
+%check
+patchelf --print-rpath %{buildroot}%{_bindir}/clang | grep -q %{_libdir}