build: Do not use backticks on m4 macros

Use single quotes for strings, angle brackets for headers, and $()
for command subsitution. This should pacify syntax highlighters.

m4/arch.m4

@@ -4,8 +4,8 @@
 # the target architecture, to avoid duplicating its logic.
 AC_DEFUN([_DPKG_ARCHITECTURE], [
 AC_REQUIRE([AC_CANONICAL_HOST])dnl
-$2=`cd $srcdir/scripts; \
-    PERL5LIB=$(pwd) ./dpkg-architecture.pl -t$host -q$1 2>/dev/null`
+$2=$(cd $srcdir/scripts; \
+    PERL5LIB=$(pwd) ./dpkg-architecture.pl -t$host -q$1 2>/dev/null)
 ])# _DPKG_ARCHITECURE
 
 # DPKG_CPU_TYPE

m4/compiler.m4

@@ -26,7 +26,7 @@ AC_DEFUN([DPKG_COMPILER_OPTIMISATIONS],
 	AS_HELP_STRING([--disable-compiler-optimisations],
 		       [Disable compiler optimisations]),
 [if test "x$enable_compiler_optimisations" = "xno"; then
-	[CFLAGS=`echo "$CFLAGS" | sed -e "s/ -O[1-9]*\b/ -O0/g"`]
+	[CFLAGS=$(echo "$CFLAGS" | sed -e "s/ -O[1-9]*\b/ -O0/g")]
 fi])dnl
 ])
 
@@ -43,7 +43,7 @@ AC_DEFUN([DPKG_C_ATTRIBUTE],
 	[dpkg_cv_attribute=no])])
 AS_IF([test "x$dpkg_cv_attribute" = "xyes"],
 	[AC_DEFINE([HAVE_C_ATTRIBUTE], 1,
-		[Define to 1 if compiler supports `__attribute__', 0 otherwise.])],
+		[Define to 1 if compiler supports '__attribute__', 0 otherwise.])],
 	[AC_DEFINE([HAVE_C_ATTRIBUTE], 0)])dnl
 ])# DPKG_C_ATTRIBUTE
 

m4/funcs.m4

@@ -18,7 +18,7 @@ exit (0);
 	[dpkg_cv_va_copy=no])])
 AS_IF([test "x$dpkg_cv_va_copy" = "xyes"],
 	[AC_DEFINE([HAVE_VA_COPY], 1,
-		  [Define to 1 if the `va_copy' macro exists])],
+		  [Define to 1 if the 'va_copy' macro exists])],
 	[AC_CACHE_CHECK([for va_list assignment by copy],
 		       [dpkg_cv_va_list_copy],
 [AC_COMPILE_IFELSE([AC_LANG_PROGRAM(

m4/libs.m4

@@ -71,9 +71,9 @@ if test "x$with_selinux" != "xno"; then
 		[AC_DEFINE(WITH_SELINUX, 1,
 			[Define to 1 to compile in SELinux support])
 		 if test "x$with_selinux" = "xstatic"; then
-			dpkg_selinux_libs="-Wl,-Bstatic "`pkg-config --static --libs libselinux`" -Wl,-Bdynamic"
+			dpkg_selinux_libs="-Wl,-Bstatic "$(pkg-config --static --libs libselinux)" -Wl,-Bdynamic"
 		 else
-			dpkg_selinux_libs=`pkg-config --libs libselinux`
+			dpkg_selinux_libs=$(pkg-config --libs libselinux)
 		 fi
 		 SELINUX_LIBS="${SELINUX_LIBS:+$SELINUX_LIBS }$dpkg_selinux_libs"
 		 with_selinux="yes"],

m4/linker.m4

@@ -8,7 +8,7 @@ AC_DEFUN([DPKG_LINKER_OPTIMISATIONS],
 	AS_HELP_STRING([--disable-linker-optimisations],
 		       [Disable linker optimisations]),
 [if test "x$enable_linker_optimisations" = "xno"; then
-	[LDFLAGS=`echo "$LDFLAGS" | sed -e "s/ -Wl,-O[0-9]*\b//g"`]
+	[LDFLAGS=$(echo "$LDFLAGS" | sed -e "s/ -Wl,-O[0-9]*\b//g")]
 else
 	[LDFLAGS="$LDFLAGS -Wl,-O1"]
 fi], [LDFLAGS="$LDFLAGS -Wl,-O1"])dnl

m4/perl.m4

@@ -5,5 +5,5 @@ AC_DEFUN([DPKG_PROG_PERL],
 [AC_ARG_VAR([PERL], [Perl interpreter])dnl
 AC_PATH_PROG([PERL], [perl], [/usr/bin/perl])dnl
 AC_ARG_VAR([PERL_LIBDIR], [Perl library directory])dnl
-PERL_LIBDIR=`$PERL -MConfig -e 'my $r=$Config{vendorlibexp};$r=~s/$Config{vendorprefixexp}/\\$(prefix)/; print $r'`dnl
+PERL_LIBDIR=$($PERL -MConfig -e 'my $r=$Config{vendorlibexp};$r=~s/$Config{vendorprefixexp}/\\$(prefix)/; print $r')dnl
 ])# DPKG_PROG_PERL

m4/types.m4

@@ -6,7 +6,7 @@
 AC_DEFUN([DPKG_TYPE_PTRDIFF_T],
 [AC_CHECK_TYPE([ptrdiff_t],,
 	AC_DEFINE_UNQUOTED([ptrdiff_t], [int],
-			   [Define to `int' if <malloc.h> does not define.]))dnl
+			   [Define to 'int' if <malloc.h> does not define.]))dnl
 ])# DPKG_TYPE_PTRDIFF_T
 
 # DPKG_DECL_SYS_SIGLIST
@@ -44,7 +44,7 @@ AC_DEFUN([DPKG_CHECK_DEFINE],
 	[dpkg_cv_define_$1=yes],
 	[dpkg_cv_define_$1=no])])
 AS_IF([test "x$dpkg_cv_define" = "xyes"],
-	[AC_DEFINE([HAVE_]$1, 1, [Define to 1 if you have the macro `]$1[' in
-				  `]$2[', and to 0 if you don't.])],
+	[AC_DEFINE([HAVE_]$1, 1, [Define to 1 if you have the macro ']$1[' in
+				  <$2>, and to 0 if you don't.])],
 	[AC_DEFINE([HAVE_]$1, 0)])[]dnl
 ])# DPKG_CHECK_DEFINE