perf build: Check whether pkg-config is installed when libtraceevent is linked

If pkg-config is not installed when libtraceevent is linked, the build fails.

The error information is as follows:

  $ make
  <SNIP>
  In file included from /home/yjh/projects_linux/perf-tool-next/linux/tools/perf/util/evsel.c:43:
  /home/yjh/projects_linux/perf-tool-next/linux/tools/perf/util/trace-event.h:149:62: error: operator '&&' has no right operand
    149 | #if defined(LIBTRACEEVENT_VERSION) &&  LIBTRACEEVENT_VERSION >= MAKE_LIBTRACEEVENT_VERSION(1, 5, 0)
        |                                                              ^~
  error: command '/usr/bin/gcc' failed with exit code 1
  cp: cannot stat 'python_ext_build/lib/perf*.so': No such file or directory
  make[2]: *** [Makefile.perf:668: python/perf.cpython-310-x86_64-linux-gnu.so] Error 1
  make[2]: *** Waiting for unfinished jobs....

Because pkg-config is not installed, fail to get libtraceevent version in
Makefile.config file. As a result, LIBTRACEEVENT_VERSION is empty.
However, the preceding error information is not user-friendly.

Identify errors in advance by checking that pkg-config is installed at
compile time.

The build results of various scenarios are as follows:

1. build successful when libtraceevent is not linked and pkg-config is not installed

  $ pkg-config --version
  -bash: /usr/bin/pkg-config: No such file or directory
  $ make clean >/dev/null
  $ make NO_LIBTRACEEVENT=1 >/dev/null
  Makefile.config:1133: No alternatives command found, you need to set JDIR= to point to the root of your Java directory
    PERF_VERSION = 6.7.rc6.gd988c9f5
  $ echo $?
  0

2. dummy pkg-config is missing when libtraceevent is linked

  $ pkg-config --version
  -bash: /usr/bin/pkg-config: No such file or directory
  $ make clean >/dev/null
  $ make >/dev/null
  Makefile.config:221: *** Error: pkg-config needed by libtraceevent is missing on this system, please install it.  Stop.
  make[1]: *** [Makefile.perf:251: sub-make] Error 2
  make: *** [Makefile:70: all] Error 2
  $ echo $?
  2

3. build successful when libtraceevent is linked and pkg-config is installed

  $ pkg-config --version
  0.29.2
  $ make clean >/dev/null
  $ make >/dev/null
  Makefile.config:1133: No alternatives command found, you need to set JDIR= to point to the root of your Java directory
    PERF_VERSION = 6.7.rc6.gd988c9f5
  $ echo $?
  0
Signed-off-by: Yang Jihong <yangjihong1@huawei.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20240112034019.3558584-1-yangjihong1@huawei.comSigned-off-by: Namhyung Kim <namhyung@kernel.org>

tools/perf/Makefile.config

@@ -216,6 +216,12 @@ ifeq ($(call get-executable,$(BISON)),)
   dummy := $(error Error: $(BISON) is missing on this system, please install it)
 endif
 
+ifneq ($(NO_LIBTRACEEVENT),1)
+  ifeq ($(call get-executable,$(PKG_CONFIG)),)
+  dummy := $(error Error: $(PKG_CONFIG) needed by libtraceevent is missing on this system, please install it)
+  endif
+endif
+
 ifneq ($(OUTPUT),)
   ifeq ($(shell expr $(shell $(BISON) --version | grep bison | sed -e 's/.\+ \([0-9]\+\).\([0-9]\+\).\([0-9]\+\)/\1\2\3/g') \>\= 371), 1)
     BISON_FILE_PREFIX_MAP := --file-prefix-map=$(OUTPUT)=