Issue 49845 - Remove pkgconfig check for libasan

Bug Description:
A recent commit introduced a pkgconfig check for libasan. However, ASAN
buildtime whereabouts are provided within compiler itself, hence there is no
external libasan.pc file, only dynamic linking to libasan is necessary.

Fix Description:
Remove the superfluous check from configure.ac.

Relates https://pagure.io/389-ds-base/issue/49845

Author: Matus Honek <[email protected]>

Review by: ???

(cherry picked from commit 031c0b9)

configure.ac

@@ -140,7 +140,6 @@ AC_ARG_ENABLE(asan, AS_HELP_STRING([--enable-asan], [Enable gcc/clang address sa
               [], [ enable_asan=no ])
 AC_MSG_RESULT($enable_asan)
 if test "$enable_asan" = yes ; then
-  PKG_CHECK_MODULES([ASAN], [libasan])
   asan_cflags="-fsanitize=address -fno-omit-frame-pointer -lasan"
   asan_rust_defs="-Z sanitizer=address"
 else