libtiff: set library version

Upstream canonically keeps this in configure.ac in current:revision:age
format, and converts it to a version number in the cmake scripts.  Mirror
the cmake logic.

Stop naming the library binary "libtiff4"; upstream doesn't do it.

Author: bgilbert

subprojects/packagefiles/libtiff/libtiff/meson.build

@@ -65,11 +65,12 @@ if host_machine.system() == 'windows'
 endif
 
 tiff4_lib = library(
-  'tiff4',
+  'tiff',
   sources,
   install: true,
   dependencies: [m_dep, jbig_dep, jpeg_dep, lerc_dep, lzma_dep, webp_dep, zlib_dep, zstd_dep],
   vs_module_defs: 'libtiff.def',
+  version: library_version,
 )
 
 install_headers(

subprojects/packagefiles/libtiff/meson.build

@@ -4,6 +4,15 @@ project(
   version: files('VERSION'),
   meson_version: '>=0.57.0',
 )
+# calculate library version from configure.ac values
+libtiff_current = 6
+libtiff_revision = 1
+libtiff_age = 0
+library_version = '@0@.@1@.@2@'.format(
+    libtiff_current - libtiff_age,
+    libtiff_age,
+    libtiff_revision
+)
 
 cc = meson.get_compiler('c')
 m_dep = cc.find_library('m', required: false)