Switch to new host prebuilt x86_64-linux-glibc2.11-4.6

Change-Id: I763398d523bf4851a13722f72b12ec69d7a4bb4f
Update build system for better Clang behavior on Mac.

Change-Id: I1813954681b670807d7e3faaf6d5f5a769cc5f2e
Build changes necessary for LLVM 3.5 switch.

Change-Id: Icb6065daada7cb1d7425206830a4ef9e23454c03

Conflicts:
	core/clang/arm.mk
Merge "Switch to new host prebuilt x86_64-linux-glibc2.11-4.6" into tools_r22.6
Merge "Update build system for better Clang behavior on Mac." into tools_r22.6
Merge "Build changes necessary for LLVM 3.5 switch." into tools_r22.6
Remove tblgen and clang-tblgen from prebuilts.

Change-Id: I89fb74da5a516d0f768f72518a401216f8a5b1a8
(cherry picked from commit 75b58cc827faad56517181960f81f5b4bd8a08f0)
Merge "Remove tblgen and clang-tblgen from prebuilts." into tools_r22.6
Revert "Remove tblgen and clang-tblgen from prebuilts." DO NOT MERGE.

This reverts commit da522500c4e76106dec5143834edca681726b5b7.
This reverts rs/bcc to the stable state of Tools r22.6.3.
Revert "Build changes necessary for LLVM 3.5 switch." DO NOT MERGE.

This reverts commit 6bd23816bf6eb5b37f785d23c5df3880d2865a60.
This reverts rs/bcc to the stable state of Tools r22.6.3.
Revert "Update build system for better Clang behavior on Mac." DO NOT MERGE.

This reverts commit c07c8fae25ffef1a97dbdba843d833ed7270f703.
This reverts rs/bcc to the stable state of Tools r22.6.3.
Revert "Switch to new host prebuilt x86_64-linux-glibc2.11-4.6" DO NOT MERGE.

This reverts commit a787d7af0699b8121ee193ab71620a626540b52d.
This reverts rs/bcc to the stable state of Tools r22.6.3.
Merge "Revert "Remove tblgen and clang-tblgen from prebuilts." DO NOT MERGE." into tools_r22.6
Merge "Revert "Build changes necessary for LLVM 3.5 switch." DO NOT MERGE." into tools_r22.6
Merge "Revert "Update build system for better Clang behavior on Mac." DO NOT MERGE." into tools_r22.6
Merge "Revert "Switch to new host prebuilt x86_64-linux-glibc2.11-4.6" DO NOT MERGE." into tools_r22.6