Add libcxx to match install-libcxx

Author: benlangmuir

utils/build-presets.ini

@@ -335,6 +335,8 @@ build-subdir=buildbot_incremental
 release
 assertions
 
+libcxx
+
 # Build llbuild & swiftpm here
 llbuild
 swiftpm
@@ -551,6 +553,7 @@ verbose-build
 # Build ninja while we are at it
 build-ninja
 
+libcxx
 llbuild
 swiftpm
 indexstore-db
@@ -985,6 +988,7 @@ mixin-preset=
     mixin_linux_install_components_with_clang
 build-subdir=buildbot_incremental
 
+libcxx
 libicu
 llbuild
 swiftpm
@@ -1325,6 +1329,8 @@ build-subdir=buildbot_incremental
 release
 assertions
 
+libcxx
+
 # Build llbuild & swiftpm here
 llbuild
 swiftpm
@@ -1393,6 +1399,8 @@ build-subdir=buildbot_incremental
 release
 assertions
 
+libcxx
+
 # Build llbuild & swiftpm here
 llbuild
 swiftpm
@@ -1431,6 +1439,7 @@ xctest
 foundation
 libdispatch
 llbuild
+libcxx
 sourcekit-lsp
 
 install-swift
@@ -1482,6 +1491,7 @@ build-subdir=buildbot_incremental
 release
 assertions
 
+libcxx
 llbuild
 swiftpm
 indexstore-db