[build] Remove libexecinfo dependency on musl builds.

muslc does not expose the frame related information to execinfo.
Compiling with libexecinfo on muslc builds doesn't really serve any purpose.

.github/actions/muslbuilder/Dockerfile

@@ -10,9 +10,7 @@ RUN apk update && apk add --no-cache \
     automake \
     build-base \
     curl \
-    git \
-    libexecinfo-dev \
-    libexecinfo-static
+    git
 
 
 RUN mkdir -p /fake.root /extract

.github/actions/muslbuilder/entrypoint.sh

@@ -18,7 +18,7 @@ cd lbuild
     CXXFLAGS='-static -g1 -gz=zlib -U__unused -no-pie -O2' \
     LDFLAGS="-L/fake.root/lib" \
     CPPFLAGS="-I/fake.root/include" \
-    LIBS="-L/fake.root/lib -lexecinfo -lssh2 -llzma -lssl -lcrypto -lz -llz4" \
+    LIBS="-L/fake.root/lib -lssh2 -llzma -lssl -lcrypto -lz -llz4" \
     --enable-static \
     PATH="/fake.root/bin:${PATH}"
 make -j2