build, doc: Drop libcap-dev from macOS cross-compiling dependencies

ci/test/00_setup_env_mac.sh

@@ -9,7 +9,7 @@ export LC_ALL=C.UTF-8
 export CONTAINER_NAME=ci_macos_cross
 export DOCKER_NAME_TAG=ubuntu:20.04  # Check that Focal can cross-compile to macos (Focal is used in the gitian build as well)
 export HOST=x86_64-apple-darwin18
-export PACKAGES="cmake imagemagick libcap-dev librsvg2-bin libz-dev libbz2-dev libtiff-tools libtinfo5 python3-dev python3-setuptools xorriso"
+export PACKAGES="cmake imagemagick librsvg2-bin libz-dev libbz2-dev libtiff-tools libtinfo5 python3-dev python3-setuptools xorriso"
 export XCODE_VERSION=11.3.1
 export XCODE_BUILD_ID=11C505
 export RUN_UNIT_TESTS=false

contrib/gitian-descriptors/gitian-osx.yml

@@ -21,7 +21,6 @@ packages:
 - "bsdmainutils"
 - "cmake"
 - "imagemagick"
-- "libcap-dev"
 - "libz-dev"
 - "libbz2-dev"
 - "python3"

depends/README.md

@@ -44,7 +44,7 @@ The paths are automatically configured and no other options are needed unless ta
 
 #### For macOS cross compilation
 
-    sudo apt-get install curl librsvg2-bin libtiff-tools bsdmainutils cmake imagemagick libcap-dev libz-dev libbz2-dev python3-setuptools libtinfo5 xorriso
+    sudo apt-get install curl librsvg2-bin libtiff-tools bsdmainutils cmake imagemagick libz-dev libbz2-dev python3-setuptools libtinfo5 xorriso
 
 #### For Win64 cross compilation