[archlinux] pacman 5.2 removal of delta support breaks pamac.

Hello.

In archlinux testing, pacman 5.2 is available. One of the main removal is delta support one.

http://allanmcrae.com/2019/10/pacman-5-2-release/

I know pacman 5.2.0 won't be in Manjaro unstable before november 2019, but I wanted to warn you early of possible bugs.

When I tried to build pamac-aur-git with pacman 5.2 - and libalpm 12 - I got this error log:

../src/alpm_utils.vala: In function 'pamac_alpm_utils_trans_commit_real':
../src/alpm_utils.vala:1361:9: error: 'ALPM_ERR_DLT_INVALID' undeclared (first use in this function); did you mean 'ALPM_ERR_DB_INVALID'?
 1361 |     switch (errno) {
      |         ^~~~~~~~~~~~        
      |         ALPM_ERR_DB_INVALID
../src/alpm_utils.vala:1361:9: note: each undeclared identifier is reported only once for each function it appears in
../src/alpm_utils.vala: In function 'cb_event':
../src/alpm_utils.vala:1756:8: error: 'ALPM_EVENT_DELTA_PATCH_START' undeclared (first use in this function); did you mean 'ALPM_EVENT_DISKSPACE_START'?
 1756 |  switch (data.type) {
      |        ^~~~~~~~~~~~~~              
      |        ALPM_EVENT_DISKSPACE_START
alpm_utils.c:12811:4: error: unknown type name 'alpm_delta_t'; did you mean 'alpm_event_t'?
alpm_utils.c:12815:4: error: unknown type name 'alpm_delta_t'; did you mean 'alpm_event_t'?
../src/alpm_utils.vala:1809:18: error: 'alpm_event_t' {aka 'union _alpm_event_t'} has no member named 'delta_patch'
 1809 |    details.add (data.delta_patch_delta.to);
      |                  ^~
../src/alpm_utils.vala:1809:21: error: request for member 'to' in something not a structure or union
 1809 |    details.add (data.delta_patch_delta.to);
      |                     ^~
../src/alpm_utils.vala:1810:18: error: 'alpm_event_t' {aka 'union _alpm_event_t'} has no member named 'delta_patch'
 1810 |    details.add (data.delta_patch_delta.delta);
      |                  ^~
../src/alpm_utils.vala:1810:21: error: request for member 'delta' in something not a structure or union
 1810 |    details.add (data.delta_patch_delta.delta);
      |                     ^~
[21/68] Compiling C object 'src/25a663...@sha/meson-generated_transaction.c.o'.
ninja: build stopped: subcommand failed.