libperf: Fix install_pkgconfig target

Commit 47e02b94 ("tools lib perf: Add dependency test to install_headers")
misses the notion of $(DESTDIR_SQ) for install_pkgconfig target, which leads to
error:

  install: cannot create regular file '/usr/lib64/pkgconfig/libperf.pc': Permission denied
  make: *** [Makefile:210: install_pkgconfig] Error 1
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Nicolas Schier <nicolas@fjasle.eu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Rix <trix@redhat.com>
Cc: bpf@vger.kernel.org
Cc: llvm@lists.linux.dev
Link: http://lore.kernel.org/lkml/Y5w/cWKyb8vpNMfA@li-4a3a4a4c-28e5-11b2-a85c-a8d192c6f089.ibm.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/lib/perf/Makefile

@@ -208,7 +208,7 @@ install_headers: $(INSTALL_HDRS) $(INSTALL_INTERNAL_HDRS)
 
 install_pkgconfig: $(LIBPERF_PC)
 	$(call QUIET_INSTALL, $(LIBPERF_PC)) \
-		$(call do_install,$(LIBPERF_PC),$(libdir_SQ)/pkgconfig,644)
+		$(call do_install,$(LIBPERF_PC),$(DESTDIR_SQ)$(libdir_SQ)/pkgconfig,644)
 
 install_doc:
 	$(Q)$(MAKE) -C Documentation install-man install-html install-examples