Patch libcurl.pc for macOS builds

cURL 8.11.0 added a couple of packages to `Requires.private`, but these
packages are irrelevant when building against a shared libcurl.  For
some reason, these private requirements are checked when we're doing
`pkg-config --cflags` (that happens with the preinstalled pkg-config
0.29.2, as well as with pkgconf 2.3.0).  To avoid further messing with
these packages, we just drop the `Requires.private` line from
libcurl.pc.

See GH-16741 for more details.

Closes GH-16783.

.github/actions/configure-macos/action.yml

@@ -18,6 +18,7 @@ runs:
         export PKG_CONFIG_PATH="$PKG_CONFIG_PATH:/usr/local/opt/libxslt/lib/pkgconfig"
         export PKG_CONFIG_PATH="$PKG_CONFIG_PATH:/usr/local/opt/zlib/lib/pkgconfig"
         export PKG_CONFIG_PATH="$PKG_CONFIG_PATH:/usr/local/opt/icu4c/lib/pkgconfig"
+        sed -i -e 's/Requires.private:.*//g' "$BREW_OPT/curl/lib/pkgconfig/libcurl.pc"
         ./buildconf --force
         ./configure \
           CFLAGS="-Wno-strict-prototypes -Wno-unused-but-set-variable -Wno-single-bit-bitfield-constant-conversion" \