[build/sysroots] Fix abi for aarch64.

Summary: Debian treats aarch64 as having an abi of gnu instead of eabi, so this diff reflects that in our build system.

Test Plan: Tested with sysroot changes. No functional changes to existing x86_64 build.

Reviewers: zasgar, vihang, michelle

Reviewed By: zasgar

Signed-off-by: James Bartlett <jamesbartlett@pixielabs.ai>

Differential Revision: https://phab.corp.pixielabs.ai/D12897

GitOrigin-RevId: 998faac16e2a48d2abe372f9119fad405b11c225

bazel/cc_toolchains/utils.bzl

@@ -17,8 +17,8 @@
 # abi returns the expected abi for the given arch libc_version pair.
 # Currently, doesn't support musl.
 def abi(arch, libc_version):
-    if arch == "aarch64":
-        return "eabi"
+    # Technically, the abi for aarch64 is eabi, however, all of the debian aarch64 sysroots we use have their files in aarch64-linux-gnu.
+    # So we treat aarch64 as having an abi of gnu as well.
     if libc_version.startswith("glibc"):
         return "gnu"