Add gcc-10 and g++-10 prereqs.

* OpenTitan dependency Mundane and BoringSSL fails to build with gcc-11

Change-Id: Ib9eccd1e457addfef37d12d5eebe35f7fd3393ef

install-prereqs.sh

diff --git a/install-prereqs.sh b/install-prereqs.sh
index 401f5de..7fc9e2e 100755
--- a/install-prereqs.sh
+++ b/install-prereqs.sh
@@ -41,7 +41,11 @@
     libcanberra-gtk-module
     libclang-dev
     libcunit1-dev
-    libc6-dev gcc g++
+    libc6-dev
+    gcc
+    g++
+    gcc-10
+    g++-10
     libftdi1
     libftdi1-dev
     libfl2
@@ -124,9 +128,7 @@
         die
     fi
 
-    pushd ${ROOTDIR}/toolchain/tockloader
-        pip3 install -e .
-    popd
+    pip3 install -e ${ROOTDIR}/toolchain/tockloader
 
     if [[ ! -z ${PYTHON_REQUIREMENTS} ]]; then
         PIP_INSTALL_ARGS=""
@@ -167,7 +169,7 @@
                 ;;
         esac
     done
-    
+
     echo "Installing apt package dependencies..."
     try_install_apt_packages