Specify branch info in .gitmodules

.gitmodules

@@ -1,21 +1,27 @@
 [submodule "riscv-binutils"]
 	path = riscv-binutils
 	url = ../riscv-binutils-gdb.git
+	branch = riscv-binutils-2.35
 [submodule "riscv-gcc"]
 	path = riscv-gcc
 	url = ../riscv-gcc.git
+	branch = riscv-gcc-10.2.0
 [submodule "riscv-glibc"]
 	path = riscv-glibc
 	url = ../riscv-glibc.git
+	branch = riscv-glibc-2.29
 [submodule "riscv-dejagnu"]
 	path = riscv-dejagnu
 	url = ../riscv-dejagnu.git
+	branch = riscv-dejagnu-1.6
 [submodule "riscv-newlib"]
 	path = riscv-newlib
 	url = git://sourceware.org/git/newlib-cygwin.git
+	branch = master
 [submodule "riscv-gdb"]
 	path = riscv-gdb
 	url = ../riscv-binutils-gdb.git
+	branch = fsf-gdb-10.1-with-sim
 [submodule "qemu"]
 	path = qemu
 	url = https://git.qemu.org/git/qemu.git