[CI] Upgrade to rustc 1.45

Remove -Zno-landing-pads flag, because it was removed in
rust-lang/rust#70175
Its replacement is panic=abort, which... we already use.

CI/tools.py

@@ -313,7 +313,6 @@ def prefix(p, s):
                 '-Zprofile',
                 '-Ccodegen-units=1',
                 '-Cinline-threshold=0',
-                '-Zno-landing-pads',
             ])
             # Build without --release
             environ['CARGO_BUILD_FLAGS'] = ''
@@ -364,9 +363,9 @@ def prefix(p, s):
             elif os == 'linux':
                 environ['CARGO_TARGET'] = 'x86_64-unknown-linux-gnu'
         if variant in ('coverage', 'asan'):
-            rust_version = 'nightly-2020-03-12'
+            rust_version = 'nightly-2020-06-05'
         else:
-            rust_version = '1.42.0'
+            rust_version = '1.45.0'
         rust_install += [
             '{rustup} install {rust_version} --profile minimal',
             'PATH={cargo_dir}:$PATH',

helper/helper.mk

@@ -173,4 +173,4 @@ compat/mingw.o: EXTRA_CPPFLAGS = -D'winansi_init()'=
 
 # Bump when CI changes need a new helper build but the helper code itself
 # hasn't changed.
-DUMMY = 1
+DUMMY = 2