Link autofdo with libLLVM

Since we are building LLVM dynamically and linking it statically,
autofdo was not able to recognize libLLVM.so correctly. This patch
changed behaviour of autofdo configuration so that it can be linked
with libLLVM.

diff --git a/m4/ax_llvm.m4 b/m4/ax_llvm.m4
index f93c873..fa0fcec 100644
--- a/m4/ax_llvm.m4
+++ b/m4/ax_llvm.m4
@@ -60,17 +60,10 @@ AC_DEFUN([AX_LLVM],
     if test -f "$ac_llvm_config_path"; then
       LLVM_CXXFLAGS=$($ac_llvm_config_path --cppflags)
       shared_mode=$($ac_llvm_config_path --shared-mode)
-      rpath=""
-      if test "x$shared_mode" = "xstatic"; then
-        LLVM_LDFLAGS="$($ac_llvm_config_path --ldflags)"
-        LLVM_LIBS="$($ac_llvm_config_path --libs $1) \
-                      -ldl -lpthread -ltinfo"
-      elif test "x$shared_mode" = "xshared"; then
-        rpath="$($ac_llvm_config_path --libdir)"
-        LLVM_LDFLAGS="-Wl,-rpath $rpath \
-                      $($ac_llvm_config_path --ldflags)"
-        LLVM_LIBS="$($ac_llvm_config_path --libs $1)"
-      fi
+      rpath="$($ac_llvm_config_path --libdir)"
+      LLVM_LDFLAGS="-Wl,-rpath $rpath \
+                   $($ac_llvm_config_path --ldflags)"
+      LLVM_LIBS="-lLLVM"
 
       AC_REQUIRE([AC_PROG_CXX])
       CXXFLAGS_SAVED="$CXXFLAGS"