Update backtrace to 0.3.40

Cargo.lock

@@ -115,9 +115,9 @@ checksum = "b671c8fb71b457dd4ae18c4ba1e59aa81793daacc361d82fcd410cef0d491875"
 
 [[package]]
 name = "backtrace"
-version = "0.3.37"
+version = "0.3.40"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5180c5a20655b14a819b652fd2378fa5f1697b6c9ddad3e695c2f9cedf6df4e2"
+checksum = "924c76597f0d9ca25d762c25a4d369d51267536465dc5064bdf0eb073ed477ea"
 dependencies = [
  "backtrace-sys",
  "cfg-if",
@@ -129,9 +129,9 @@ dependencies = [
 
 [[package]]
 name = "backtrace-sys"
-version = "0.1.30"
+version = "0.1.32"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5b3a000b9c543553af61bc01cbfc403b04b5caa9e421033866f2e98061eb3e61"
+checksum = "5d6575f128516de27e3ce99689419835fce9643a9b215a14d2b5b685be018491"
 dependencies = [
  "cc",
  "compiler_builtins",
@@ -391,9 +391,9 @@ version = "0.1.0"
 
 [[package]]
 name = "cc"
-version = "1.0.35"
+version = "1.0.37"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5e5f3fee5eeb60324c2781f1e41286bdee933850fff9b3c672587fed5ec58c83"
+checksum = "39f75544d7bbaf57560d2168f28fd649ff9c76153874db88bdbdfd839b1a7e7d"
 
 [[package]]
 name = "cfg-if"
@@ -3113,6 +3113,7 @@ dependencies = [
  "backtrace",
  "bitflags",
  "byteorder",
+ "cc",
  "chalk-engine",
  "fmt_macros",
  "graphviz",

src/librustc/Cargo.toml

@@ -10,6 +10,10 @@ path = "lib.rs"
 doctest = false
 
 [dependencies]
+# Prevent cc from upgrading all the way to 1.0.46,
+# which fails the build (see e.g. #65445.)
+cc = "=1.0.37"
+
 arena = { path = "../libarena" }
 bitflags = "1.0"
 fmt_macros = { path = "../libfmt_macros" }
@@ -30,7 +34,7 @@ errors = { path = "../librustc_errors", package = "rustc_errors" }
 rustc_serialize = { path = "../libserialize", package = "serialize" }
 syntax = { path = "../libsyntax" }
 syntax_pos = { path = "../libsyntax_pos" }
-backtrace = "0.3.3"
+backtrace = "0.3.40"
 parking_lot = "0.9"
 byteorder = { version = "1.3" }
 chalk-engine = { version = "0.9.0", default-features=false }