Support gprof and symbols options to the Linux build.

build/SConscript.main

Index: build/SConscript.main
diff --git a/build/SConscript.main b/build/SConscript.main
index 0fb14d42bf638b37b96e7f589ae979ce1765ca4a..6af08a901c94c2c406cebc2f42531959849bf18a 100644
--- a/build/SConscript.main
+++ b/build/SConscript.main
@@ -468,6 +468,15 @@ if ARGUMENTS.get('COVERAGE') == '1':
   linux_env.Append(CCFLAGS=['-fprofile-arcs', '-ftest-coverage'])
   linux_env.Append(LINKFLAGS=['-fprofile-arcs'])
 
+# Build with support for gprof when PROFILE=1.
+if ARGUMENTS.get('PROFILE') == '1':
+  linux_env.Append(CCFLAGS=['-pg', '-g'])
+  linux_env.Append(LINKFLAGS=['-pg'])
+
+# Build with symbols (useful for opt builds, for example) when SYMBOLS=1.
+if ARGUMENTS.get('SYMBOLS') == '1':
+  linux_env.Append(CCFLAGS=['-g'])
+
 # Build with system-provided NSS and GTK.
 if root_env['PLATFORM'] in ['linux', 'linux2', 'posix']:
   try: