Pull nasm from github

... instead of nasm.us, which seems to be down. Drop back to the 2.15.x
series until we can eliminate older CI nodes with an older version of
autoconf.

Change-Id: I75242ff5ad2e6259e26d084798c71467fbf7fb3c

Dockerfile

@@ -37,9 +37,8 @@ RUN if [ -n "$(type -p yum)" ]; then yum install -y zlib-devel ; fi
 # Not *too far*, though, since we've got the old base image
 RUN /opt/_internal/tools/bin/pip install -U 'auditwheel<5.2'
 
-# Server includes `Content-Encoding: x-gzip`, so ADD unwraps it
-ADD https://www.nasm.us/pub/nasm/releasebuilds/2.16.01/nasm-2.16.01.tar.gz /opt/src/nasm.tar
-RUN tar -C /opt/src -x -f /opt/src/nasm.tar
+ADD https://github.com/netwide-assembler/nasm/archive/refs/tags/nasm-2.15.05.tar.gz /opt/src/nasm.tar.gz
+RUN tar -C /opt/src -xz -f /opt/src/nasm.tar.gz
 RUN cd /opt/src/nasm-* && \
     ./autogen.sh && \
     ./configure --prefix=/usr && \

tools/pip-install-with-liberasurecode.sh

@@ -6,12 +6,9 @@ fi
 
 if [ -n "$NASM_DIR" ]; then
     if [ ! -d "$NASM_DIR" ]; then
-        mkdir -p "$NASM_DIR"
-        pushd "$NASM_DIR"
-        curl https://www.nasm.us/pub/nasm/releasebuilds/2.16.01/nasm-2.16.01.tar.gz | tar -xz
-        popd
+        git clone https://github.com/netwide-assembler/nasm.git -b nasm-2.15.05 "$NASM_DIR"
     fi
-    pushd "$NASM_DIR"/nasm*
+    pushd "$NASM_DIR"
     ./autogen.sh
     ./configure --prefix "$VIRTUAL_ENV"
     make nasm