Remove configure --with-CC option

It's been deprecated since commit cb292206c5 from July 2000.

Discussion: https://www.postgresql.org/message-id/a2a0f5d8-2d80-48e5-b8f7-0a0a6018c3b7@iki.fi

configure

@@ -845,7 +845,6 @@ with_blocksize
 with_segsize
 with_segsize_blocks
 with_wal_blocksize
-with_CC
 with_llvm
 enable_depend
 enable_cassert
@@ -1557,7 +1556,6 @@ Optional Packages:
                           set table segment size in blocks [0]
   --with-wal-blocksize=BLOCKSIZE
                           set WAL block size in kB [8]
-  --with-CC=CMD           set compiler (deprecated)
   --with-llvm             build with LLVM based JIT support
   --without-icu           build without ICU support
   --with-tcl              build Tcl modules (PL/Tcl)
@@ -3891,31 +3889,6 @@ _ACEOF
 # C compiler
 #
 
-# For historical reasons you can also use --with-CC to specify the C compiler
-# to use, although the standard way to do this is to set the CC environment
-# variable.
-
-
-
-# Check whether --with-CC was given.
-if test "${with_CC+set}" = set; then :
-  withval=$with_CC;
-  case $withval in
-    yes)
-      as_fn_error $? "argument required for --with-CC option" "$LINENO" 5
-      ;;
-    no)
-      as_fn_error $? "argument required for --with-CC option" "$LINENO" 5
-      ;;
-    *)
-      CC=$with_CC
-      ;;
-  esac
-
-fi
-
-
-
 # If you don't specify a list of compilers to test, the AC_PROG_CC and
 # AC_PROG_CXX macros test for a long list of unsupported compilers.
 pgac_cc_list="gcc cc"

configure.ac

@@ -368,11 +368,6 @@ AC_DEFINE_UNQUOTED([XLOG_BLCKSZ], ${XLOG_BLCKSZ}, [
 # C compiler
 #
 
-# For historical reasons you can also use --with-CC to specify the C compiler
-# to use, although the standard way to do this is to set the CC environment
-# variable.
-PGAC_ARG_REQ(with, CC, [CMD], [set compiler (deprecated)], [CC=$with_CC])
-
 # If you don't specify a list of compilers to test, the AC_PROG_CC and
 # AC_PROG_CXX macros test for a long list of unsupported compilers.
 pgac_cc_list="gcc cc"