fix: use absolute paths for boringssl include symlink

Relative symlink target resolves relative to the link's own location,
not cwd where ln was invoked. quiche/deps/boringssl/src/include
pointing at 'target/release/build/...' resolved to
quiche/deps/boringssl/src/target/release/build/... (does not exist) —
curl ./configure rejected the prefix because dereferencing the
include symlink failed.

Use absolute /opt/quiche-src/... for both find input and ln target.

Author: dvershinin

Dockerfile

@@ -22,10 +22,10 @@ RUN cd /opt/quiche-src && \
     RUST_BACKTRACE=1 PATH="$HOME/.cargo/bin:$PATH" RUSTFLAGS="-C target-feature=-crt-static" cargo build -vv --package quiche --release --features ffi,pkg-config-meta,qlog --jobs $(nproc) && \
     mkdir -p quiche/deps/boringssl/src/lib && \
     ln -vnf $(find target/release -name libcrypto.a -o -name libssl.a) quiche/deps/boringssl/src/lib/ && \
-    BORING_SSL_H=$(find target/release/build -path "*/boring-sys-*/*" -name ssl.h -path "*/openssl/*" | head -1) && \
+    BORING_SSL_H=$(find /opt/quiche-src/target/release/build -path "*/boring-sys-*/*" -name ssl.h -path "*/openssl/*" | head -1) && \
     BORING_INC=$(dirname $(dirname "$BORING_SSL_H")) && \
     test -n "$BORING_INC" && test -d "$BORING_INC" && \
-    ln -vnsfT "$BORING_INC" quiche/deps/boringssl/src/include
+    ln -vnsfT "$BORING_INC" /opt/quiche-src/quiche/deps/boringssl/src/include
 
 RUN mkdir -p /opt/curl-src && \
     tar -xzf /opt/curl.tar.gz -C /opt/curl-src --strip-components=1 && \