Use valgrind built with gcc-4.9-glibc-2.20

Summary:
Right now we use valgrind built with gcc-5-glibc-2.23 which keep generating this error everywhere

```
==3224756== Conditional jump or move depends on uninitialised value(s)
==3224756==    at 0x401AD68: index (in /usr/local/fbcode/gcc-4.9-glibc-2.20/lib/ld-2.20.so)
==3224756==    by 0x4008933: _dl_map_object (in /usr/local/fbcode/gcc-4.9-glibc-2.20/lib/ld-2.20.so)
==3224756==    by 0x4000ECC: map_doit (in /usr/local/fbcode/gcc-4.9-glibc-2.20/lib/ld-2.20.so)
==3224756==    by 0x40101C7: _dl_catch_error (in /usr/local/fbcode/gcc-4.9-glibc-2.20/lib/ld-2.20.so)
==3224756==    by 0x4000B34: do_preload (in /usr/local/fbcode/gcc-4.9-glibc-2.20/lib/ld-2.20.so)
==3224756==    by 0x400458C: dl_main (in /usr/local/fbcode/gcc-4.9-glibc-2.20/lib/ld-2.20.so)
==3224756==    by 0x40185DB: _dl_sysdep_start (in /usr/local/fbcode/gcc-4.9-glibc-2.20/lib/ld-2.20.so)
==3224756==    by 0x4004F39: _dl_start (in /usr/local/fbcode/gcc-4.9-glibc-2.20/lib/ld-2.20.so)
==3224756==    by 0x4000CE7: ??? (in /usr/local/fbcode/gcc-4.9-glibc-2.20/lib/ld-2.20.so)
==3224756==  Uninitialised value was created by a stack allocation
==3224756==    at 0x4004519: dl_main (in /usr/local/fbcode/gcc-4.9-glibc-2.20/lib/ld-2.20.so)
==3224756==
```

Test Plan: DISABLE_JEMALLOC=1 make valgrind_check -j64

Reviewers: andrewkr, yiwu, sdong

Reviewed By: sdong

Subscribers: andrewkr, dhruba

Differential Revision: https://reviews.facebook.net/D59343

build_tools/dependencies.sh

@@ -13,4 +13,4 @@ NUMA_BASE=/mnt/gvfs/third-party2/numa/1abc0d3c01743b854676423cf2d3629912f34930/2
 LIBUNWIND_BASE=/mnt/gvfs/third-party2/libunwind/ad576de2a1ea560c4d3434304f0fc4e079bede42/trunk/gcc-5-glibc-2.23/b1847cb
 KERNEL_HEADERS_BASE=/mnt/gvfs/third-party2/kernel-headers/f24be37d170e04be6e469af487644d4d62e1c6c1/4.0.9-36_fbk5_2933_gd092e3f/gcc-5-glibc-2.23/da39a3e
 BINUTILS_BASE=/mnt/gvfs/third-party2/binutils/9d65c666b9adf8f2a989fd4b98a9a5e7d3afa233/2.26/centos6-native/da39a3e
-VALGRIND_BASE=/mnt/gvfs/third-party2/valgrind/9cee5a3628dc9d4b93897972c58eba865e25b270/3.11.0/gcc-5-glibc-2.23/9bc6787
+VALGRIND_BASE=/mnt/gvfs/third-party2/valgrind/9cee5a3628dc9d4b93897972c58eba865e25b270/3.10.0/gcc-4.9-glibc-2.20/e9936bf

build_tools/update_dependencies.sh

@@ -85,7 +85,7 @@ get_lib_base libunwind  LATEST
 
 get_lib_base kernel-headers LATEST 
 get_lib_base binutils   LATEST centos6-native 
-get_lib_base valgrind   LATEST
+get_lib_base valgrind   3.10.0 gcc-4.9-glibc-2.20
 
 git diff $OUTPUT