remove checksum; commit hash is sufficient

.SRCINFO

@@ -63,7 +63,7 @@ pkgbase = icecat
 	options = !strip
 	source = gnuzilla-140.4.0-579bc28.tar.gz::https://cgit.git.savannah.gnu.org/cgit/gnuzilla.git/snapshot/gnuzilla-579bc2897077119e38a7e1493bca6ec97a06a36a.tar.gz
 	source = https://archive.mozilla.org/pub/firefox/releases/140.4.0esr/source/firefox-140.4.0esr.source.tar.xz
-	sha256sums = 66f1b6a5962756d01a412fa3f19641ab7b4915bb9f6075e41c1b4fddcb3a6d0f
+	sha256sums = SKIP
 	sha256sums = 49f20673171046bc7b64f4caa340c46e1e105b9107f0ef68b7a94f379bcea4f7
 
 pkgname = icecat

PKGBUILD

@@ -26,7 +26,6 @@
 ## update
 _icver="140.4.0"
 _commit="579bc2897077119e38a7e1493bca6ec97a06a36a" # 140.4.0.r2
-_icsum="66f1b6a5962756d01a412fa3f19641ab7b4915bb9f6075e41c1b4fddcb3a6d0f"
 _ffsum="49f20673171046bc7b64f4caa340c46e1e105b9107f0ef68b7a94f379bcea4f7"
 
 ## package
@@ -130,7 +129,7 @@ _source_icecat() {
     "https://archive.mozilla.org/pub/firefox/releases/${pkgver}esr/source/firefox-${pkgver}esr.source.tar.xz"
   )
   sha256sums=(
-    "$_icsum"
+    'SKIP'
     "$_ffsum"
   )
 }
@@ -333,7 +332,7 @@ END
 )
 
 build() (
-  _run_if_exists _prepare_icecat
+  _prepare_icecat
 
   cd "$_pkgsrc"
 
@@ -570,9 +569,3 @@ END
       "$pkgdir/usr/share/icons/hicolor/${i}x${i}/apps/$_pkgname.png"
   done
 }
-
-_run_if_exists() {
-  if declare -F "$1" > /dev/null; then
-    eval "$1"
-  fi
-}