[PATCH] gdb/README: Document GNU Make requirement

[Guinevere Larsen <guinevere@redhat.com>]

User la_mettrie on IRC mentioned that they were having difficulties
building GDB, and after some debugging, we figured out that they weren't
using GNU Make. This is in the final documentation, but considering that
it is not an obvious place to look, and the README mentions other build
requirements, so this seems like a pretty obvious oversight.
---
 gdb/README | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/gdb/README b/gdb/README
index 492b0891668..09c88bcd19c 100644
--- a/gdb/README
+++ b/gdb/README
@@ -86,8 +86,8 @@ configure the build tree.)
 C++17 compiler for your system, you may be able to download and install
 the GNU CC compiler.  It is available via anonymous FTP from the
 directory `ftp://ftp.gnu.org/pub/gnu/gcc'.  GDB also requires an ISO
-C standard library.  The GDB remote server, GDBserver, builds with some
-non-ISO standard libraries - e.g. for Windows CE.
+C standard library and GNU Make.  The GDB remote server, GDBserver,
+builds with some non-ISO standard libraries - e.g. for Windows CE.
 
    GDB can optionally be built against various external libraries.
 These dependencies are described below in the "`configure options"

base-commit: 7c5179caca8cbca0f2fdb64f0fe215cee803ccb3
prerequisite-patch-id: 47ca70553d73d20b7f4c648078529a2bb301eb64
-- 
2.53.0