gh-40577: Meson: use pkg-config for more libraries
    
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Use the new pkgconfig files of sirocco, homfly, brial, ...

I didn't test that it's indeed discovering the new pkg-config files and
that compilation is successful.

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- [ ] I have created tests covering the changes.
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### ⌛ Dependencies

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URL: #40577
Reported by: Tobias Diez
Reviewer(s): Dima Pasechnik

Author: Release Manager

src/meson.build

@@ -148,13 +148,16 @@ if not m4rie.found()
   # For some reason, m4rie is not found via pkg-config on some systems (eg Conda)
   m4rie = cc.find_library('m4rie', required: not is_windows, disabler: true)
 endif
-# Cannot be found via pkg-config
-mtx = cc.find_library(
-  'mtx',
-  required: get_option('meataxe'),
-  disabler: true,
-  has_headers: ['meataxe.h'],
-)
+mtx = dependency('mtx', required: false)
+if not mtx.found()
+  # fallback for older versions without pkg-config
+  mtx = cc.find_library(
+    'mtx',
+    required: get_option('meataxe'),
+    disabler: true,
+    has_headers: ['meataxe.h'],
+  )
+endif
 png = dependency(['libpng', 'png', 'png16'], version: '>=1.2')
 zlib = dependency('zlib', version: '>=1.2.11')
 # We actually want >= 20231212, but the version number is not updated in the pkgconfig

src/sage/graphs/meson.build

@@ -5,14 +5,22 @@ if cc.has_header('mcqd.h', required: get_option('mcqd'))
   # mcqd is a header-only library
   mcqd = declare_dependency()
 endif
-cliquer = cc.find_library('cliquer', required: not is_windows, disabler: true)
 
-# Cannot be found via pkg-config
-planarity = cc.find_library(
-  'planarity',
-  required: not is_windows,
-  disabler: true,
-)
+cliquer = dependency('libcliquer', required: false, disabler: true)
+if not cliquer.found()
+  # fallback for older versions without pkg-config
+  cliquer = cc.find_library('cliquer', required: not is_windows, disabler: true)
+endif
+
+planarity = dependency('libplanarity', required: false, disabler: true)
+if not planarity.found()
+  # fallback for older versions without pkg-config
+  planarity = cc.find_library(
+    'planarity',
+    required: not is_windows,
+    disabler: true,
+  )
+endif
 
 py.install_sources(
   '__init__.py',

src/sage/libs/meson.build

@@ -1,8 +1,12 @@
-sirocco = cc.find_library(
-  'sirocco',
-  required: get_option('sirocco'),
-  disabler: true,
-)
+sirocco = dependency('libsirocco', required: false, disabler: true)
+if not sirocco.found()
+  # fallback for older versions without pkg-config
+  sirocco = cc.find_library(
+    'sirocco',
+    required: get_option('sirocco'),
+    disabler: true,
+  )
+endif
 # cannot be found via pkg-config
 ecl = cc.find_library('ecl', required: false, disabler: true)
 if not ecl.found() and not is_windows
@@ -81,12 +85,16 @@ gc = dependency(
   required: not is_windows,
   disabler: true,
 )
-homfly = cc.find_library(
-  'homfly',
-  has_headers: ['homfly.h'],
-  required: false,
-  disabler: true,
-)
+homfly = dependency('libhomfly', required: false, disabler: true)
+if not homfly.found()
+  # fallback for older versions without pkg-config
+  homfly = cc.find_library(
+    'homfly',
+    has_headers: ['homfly.h'],
+    required: false,
+    disabler: true,
+  )
+endif
 
 py.install_sources(
   '__init__.py',

src/sage/libs/symmetrica/meson.build

@@ -1,9 +1,12 @@
-# Cannot be found by pkg-config
-symmetrica = cc.find_library(
-  'symmetrica',
-  required: not is_windows,
-  disabler: true,
-)
+symmetrica = dependency('symmetrica', required: false, disabler: true)
+if not symmetrica.found()
+  # fallback for older versions without pkg-config
+  symmetrica = cc.find_library(
+    'symmetrica',
+    required: not is_windows,
+    disabler: true,
+  )
+endif
 
 py.install_sources('__init__.py', 'all.py', subdir: 'sage/libs/symmetrica')
 

src/sage/rings/polynomial/pbori/meson.build

@@ -1,4 +1,8 @@
-brial = cc.find_library('brial', required: get_option('brial'), disabler: true)
+brial = dependency('brial', required: false, disabler: true)
+if not brial.found()
+  # fallback for older versions without pkg-config
+  brial = cc.find_library('brial', required: get_option('brial'), disabler: true)
+endif
 # Cannot be found via pkg-config
 brial_groebner = cc.find_library(
   'brial_groebner',