[PATCH] tools/perf: fix use of alternatives to find JDIR

[Jarod Wilson <jarod@redhat.com>]

When a build is run from something like a cron job, the user's $PATH is
rather minimal, of note, not including /usr/sbin in my own case. Because
of that, an automated rpm package build ultimately fails to find
libperf-jvmti.so, because somewhere within the build, this happens...

/bin/sh: alternatives: command not found
/bin/sh: alternatives: command not found
Makefile.config:849: No openjdk development package found, please install
JDK package, e.g. openjdk-8-jdk, java-1.8.0-openjdk-devel

...and while the build continues, libperf-jvmti.so isn't built, and things
fall down when rpm tries to find all the %files specified. Exact same
system builds everything just fine when the job is launched from a login
shell instead of a cron job, since alternatives is in $PATH, so openjdk is
actually found.

The test required to get into this section of code actually specifies the
full path, as does a block just above it, so let's do that here too.

CC: Peter Zijlstra <peterz@infradead.org>
CC: Ingo Molnar <mingo@redhat.com>
CC: Arnaldo Carvalho de Melo <acme@kernel.org>
CC: Alexander Shishkin <alexander.shishkin@linux.intel.com>
CC: Jiri Olsa <jolsa@redhat.com>
CC: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Jarod Wilson <jarod@redhat.com>
---
 tools/perf/Makefile.config | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index f6d1a03c7523..e30d20fb482d 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -833,7 +833,7 @@ ifndef NO_JVMTI
     JDIR=$(shell /usr/sbin/update-java-alternatives -l | head -1 | awk '{print $$3}')
   else
     ifneq (,$(wildcard /usr/sbin/alternatives))
-      JDIR=$(shell alternatives --display java | tail -1 | cut -d' ' -f 5 | sed 's%/jre/bin/java.%%g')
+      JDIR=$(shell /usr/sbin/alternatives --display java | tail -1 | cut -d' ' -f 5 | sed 's%/jre/bin/java.%%g')
     endif
   endif
   ifndef JDIR
-- 
2.16.1