refactor: Introduce a virtual manifest

Move the workspace configuration to a virtual manifest. This
reorganization makes a more clear separation between package contents
and support files that don't get distributed. It will also make it
easier to merge this repository with `compiler-builtins` if that is done
at some point, which had a similar update done in [1].

LICENSE.txt and README.md are symlinkedinto the new directory to ensure
they get included in the package.

[1]: rust-lang/compiler-builtins#702

Author: tgross35

Cargo.toml

@@ -0,0 +1,37 @@
+[workspace]
+resolver = "2"
+members = [
+  "libm",
+  "crates/libm-macros",
+  "crates/libm-test",
+  "crates/musl-math-sys",
+  "crates/util",
+]
+default-members = [
+  "libm",
+  "crates/libm-macros",
+  "crates/libm-test"
+]
+exclude = [
+  # Requires `panic = abort` so can't be a member of the workspace
+  "crates/compiler-builtins-smoke-test",
+]
+
+# The default release profile is unchanged.
+
+# Release mode with debug assertions
+[profile.release-checked]
+inherits = "release"
+debug-assertions = true
+overflow-checks = true
+
+# Release with maximum optimizations, which is very slow to build. This is also
+# what is needed to check `no-panic`.
+[profile.release-opt]
+inherits = "release"
+codegen-units = 1
+lto = "fat"
+
+[profile.bench]
+# Required for iai-callgrind
+debug = true

ci/ci-util.py

@@ -24,7 +24,7 @@
     COMMAND:
         generate-matrix
             Calculate a matrix of which functions had source change, print that as
-             a JSON object.
+            a JSON object.
 
         locate-baseline [--download] [--extract]
             Locate the most recent benchmark baseline available in CI and, if flags