perf jvmti: Link against tools/lib/ctype.h to have weak strlcpy()

The build of file libperf-jvmti.so succeeds but the resulting
object fails to load:

 # ~/linux/tools/perf/perf record -k mono -- java  \
      -XX:+PreserveFramePointer \
      -agentpath:/root/linux/tools/perf/libperf-jvmti.so \
       hog 100000 123450
  Error occurred during initialization of VM
  Could not find agent library /root/linux/tools/perf/libperf-jvmti.so
      in absolute path, with error:
      /root/linux/tools/perf/libperf-jvmti.so: undefined symbol: _ctype

Add the missing _ctype symbol into the build script.

Fixes: 79743bc9 ("perf jvmti: Link against tools/lib/string.o to have weak strlcpy()")
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Link: http://lore.kernel.org/lkml/20191008093841.59387-1-tmricht@linux.ibm.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/jvmti/Build

@@ -2,7 +2,7 @@ jvmti-y += libjvmti.o
 jvmti-y += jvmti_agent.o
 
 # For strlcpy
-jvmti-y += libstring.o
+jvmti-y += libstring.o libctype.o
 
 CFLAGS_jvmti         = -fPIC -DPIC -I$(JDIR)/include -I$(JDIR)/include/linux
 CFLAGS_REMOVE_jvmti  = -Wmissing-declarations
@@ -15,3 +15,7 @@ CFLAGS_libstring.o += -Wno-unused-parameter -DETC_PERFCONFIG="BUILD_STR($(ETC_PE
 $(OUTPUT)jvmti/libstring.o: ../lib/string.c FORCE
 	$(call rule_mkdir)
 	$(call if_changed_dep,cc_o_c)
+
+$(OUTPUT)jvmti/libctype.o: ../lib/ctype.c FORCE
+	$(call rule_mkdir)
+	$(call if_changed_dep,cc_o_c)