Update stdlib source paths

In 1.47.0, some crates have been moved to the library/ source directory.
Update our list of copied sources to reflect that change.

Bug: 171280890
Change-Id: If49360002bdd5ebbf46a65bdec396d8538248b4a

Author: tweksteen

build.py

@@ -30,19 +30,19 @@
 
 
 STDLIB_SOURCES = [
-        "src/liballoc",
-        "src/libcore",
-        "src/libpanic_abort",
-        "src/libpanic_unwind",
-        "src/libproc_macro",
-        "src/libprofiler_builtins",
-        "src/libstd",
-        "src/libterm",
-        "src/libtest",
-        "src/libunwind",
-        "src/stdarch",
+        "library/alloc",
+        "library/backtrace",
+        "library/core",
+        "library/panic_abort",
+        "library/panic_unwind",
+        "library/proc_macro",
+        "library/profiler_builtins",
+        "library/std",
+        "library/stdarch",
+        "library/term",
+        "library/test",
+        "library/unwind",
         "vendor/backtrace",
-        "vendor/backtrace-sys",
         "vendor/cfg-if",
         "vendor/compiler_builtins",
         "vendor/getopts",