Fix some broken links under bootstrapping. (#1958)

* Fix some broken links under bootstrapping.

* Fix more broken links for bootstrapping.

src/appendix/glossary.md

@@ -78,7 +78,7 @@ Term                                                  | Meaning
 <span id="soundness">soundness</span>          &nbsp; |  A technical term in type theory. Roughly, if a type system is sound, then a program that type-checks is type-safe. That is, one can never (in safe rust) force a value into a variable of the wrong type. (see "completeness").
 <span id="span">span</span>                    &nbsp; |  A location in the user's source code, used for error reporting primarily. These are like a file-name/line-number/column tuple on steroids: they carry a start/end point, and also track macro expansions and compiler desugaring. All while being packed into a few bytes (really, it's an index into a table). See the [`Span`] datatype for more.
 <span id="substs">substs</span>                &nbsp; |  The substitutions for a given generic type or item (e.g. the `i32`, `u32` in `HashMap<i32, u32>`).
-<span id="sysroot">sysroot</span>              &nbsp; |  The directory for build artifacts that are loaded by the compiler at runtime. ([see more](../building/bootstrapping.html#what-is-a-sysroot))
+<span id="sysroot">sysroot</span>              &nbsp; |  The directory for build artifacts that are loaded by the compiler at runtime. ([see more](../building/bootstrapping/what-bootstrapping-does.html#what-is-a-sysroot))
 <span id="tag">tag</span>                      &nbsp; |  The "tag" of an enum/generator encodes the [discriminant](#discriminant) of the active variant/state.  Tags can either be "direct" (simply storing the discriminant in a field) or use a ["niche"](#niche).
 <span id="tait">TAIT</span>                    &nbsp; |  A type-alias `impl Trait`. Introduced in [RFC 2515](https://rust-lang.github.io/rfcs/2515-type_alias_impl_trait.html).
 <span id="tcx">`tcx`</span>                    &nbsp; |  Standard variable name for the "typing context" (`TyCtxt`), main data structure of the compiler. ([see more](../ty.md))

src/backend/libs-and-metadata.md

@@ -164,7 +164,7 @@ compilation.
 [`CStore`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_metadata/creader/struct.CStore.html
 [`CrateMetadata`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_metadata/rmeta/decoder/struct.CrateMetadata.html
 [`GlobalCtxt`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/struct.GlobalCtxt.html
-[sysroot]: ../building/bootstrapping.md#what-is-a-sysroot
+[sysroot]: ../building/bootstrapping/what-bootstrapping-does.md#what-is-a-sysroot
 
 ## Pipelining
 

src/building/bootstrapping/what-bootstrapping-does.md

@@ -85,7 +85,7 @@ because one must first build the new compiler with an older compiler
 and then use that to build the new compiler with itself.
 For development, you usually only want the `stage1` compiler,
 which you can build with `./x build library`.
-See [Building the compiler](./how-to-build-and-run.html#building-the-compiler).
+See [Building the compiler](../how-to-build-and-run.html#building-the-compiler).
 
 ### Stage 3: the same-result test
 
@@ -131,7 +131,7 @@ a compiler that's not nightly. This should never be used except when
 bootstrapping the compiler.
 
 [boot]: https://en.wikipedia.org/wiki/Bootstrapping_(compilers)
-[intrinsics]: ../appendix/glossary.md#intrinsic
+[intrinsics]: ../../appendix/glossary.md#intrinsic
 [ocaml-compiler]: https://github.com/rust-lang/rust/tree/ef75860a0a72f79f97216f8aaa5b388d98da6480/src/boot
 
 ## Understanding stages of bootstrap
@@ -157,7 +157,7 @@ Build artifacts include, but are not limited to:
 - [rlib] files, like `stage0-sysroot/rustlib/libstd-6fae108520cf72fe.rlib`
 - HTML files generated by rustdoc, like `doc/std`
 
-[rlib]: ../serialization.md
+[rlib]: ../../serialization.md
 
 #### Examples
 
@@ -390,7 +390,7 @@ method][env-vars] of configuring C compilers and C flags via environment
 variables.
 
 [cc-rs crate]: https://github.com/rust-lang/cc-rs
-[env-vars]: https://github.com/rust-lang/cc-rs#external-configuration-via-environment-variables
+[env-vars]: https://docs.rs/cc/latest/cc/#external-configuration-via-environment-variables
 
 ## Clarification of build command's stdout
 

src/compiler-src.md

@@ -173,7 +173,7 @@ from `src/tools/`, such as [`tidy`] or [`compiletest`].
 [`tidy`]: https://github.com/rust-lang/rust/tree/master/src/tools/tidy
 [`compiletest`]: https://github.com/rust-lang/rust/tree/master/src/tools/compiletest
 
-[bootstch]: ./building/bootstrapping.md
+[bootstch]: ./building/bootstrapping/intro.md
 
 ## Standard library
 

src/overview.md

@@ -370,7 +370,7 @@ For more details on bootstrapping, see
 [the bootstrapping section of the guide][rustc-bootstrap].
 
 [_bootstrapping_]: https://en.wikipedia.org/wiki/Bootstrapping_(compilers)
-[rustc-bootstrap]: building/bootstrapping.md
+[rustc-bootstrap]: building/bootstrapping/intro.md
 
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