add cpu profile

+cpu_profiler: cpu_profiler.cc Makefile
+	g++ -o cpu_profiler cpu_profiler.cc -g -O0 -ansi \
+        -fno-builtin-malloc -fno-builtin-calloc -fno-builtin-realloc -fno-builtin-free \
+        -I../../../objs/gperf/include ../../../objs/gperf/lib/libtcmalloc_and_profiler.a -lpthread
+clean:
+	rm -f cpu_profiler ./srs.conf*

+/*
+The MIT License (MIT)
+
+Copyright (c) 2013-2014 winlin
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software is furnished to do so,
+subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*/
+/**
+set the pprof path if not set:
+    export PPROF_PATH=`pwd`/../../../objs/pprof
+to do cpu profile:
+    make && rm -f ./srs.conf* && env CPUPROFILE=./srs.conf ./cpu_profiler
+    $PPROF_PATH --text cpu_profiler ./srs.conf*
+to do cpu profile by signal:
+    make && rm -f ./srs.conf* && env CPUPROFILE=./srs.conf CPUPROFILESIGNAL=12 ./cpu_profiler
+    $PPROF_PATH --text cpu_profiler ./srs.conf*
+*/
+#include <stdio.h>
+#include <unistd.h>
+#include <signal.h>
+#include <stdlib.h>
+
+#include <gperftools/profiler.h>
+
+void cpu_profile_imp() {
+    for (int i = 0; i < 2; ++i) {
+        for (int j = 0; j < 110 * 1024 * 1024; ++j) {
+        }
+        printf("cpu profile, loop 110M\n");
+        printf("press CTRL+C if you want to abort the program.\n");
+        sleep(3);
+    }
+}
+void cpu_profile() {
+    cpu_profile_imp();
+}
+
+void handler(int sig) {
+    exit(0);
+}
+int main(int argc, char** argv) {
+    signal(SIGINT, handler);
+    
+    // must start profiler manually.
+    ProfilerStart(NULL);
+    
+    if (getenv("CPUPROFILESIGNAL")) {
+        printf("if specified CPUPROFILESIGNAL, use signal to active it: kill -12 %d\n", getpid());
+        sleep(3);
+    }
+    
+    cpu_profile();
+    // not neccessary to call stop.
+    //ProfilerStop();
+    
+    return 0;
+}
+