Add all.sh run with MBEDTLS_MEMORY_BUFFER_ALLOC_C enabled

With the removal of MBEDTLS_MEMORY_BUFFER_ALLOC_C from the
full config, there are no tests for it remaining in all.sh.
This commit adds a build as well as runs of `make test` and
`ssl-opt.sh` with MBEDTLS_MEMORY_BUFFER_ALLOC_C enabled to all.sh.
diff --git a/tests/scripts/all.sh b/tests/scripts/all.sh
index 6a10500..a0c3ef4 100755
--- a/tests/scripts/all.sh
+++ b/tests/scripts/all.sh
@@ -959,6 +959,20 @@
     make CC=gcc CFLAGS='-Werror -Wall -Wextra -O0 -std=c99 -pedantic' lib
 }
 
+component_test_memory_buffer_allocator () {
+    msg "build: default config with memory buffer allocator enabled"
+    scripts/config.pl set MBEDTLS_MEMORY_BUFFER_ALLOC_C
+    scripts/config.pl set MBEDTLS_MEMORY_BACKTRACE
+    CC=gcc cmake .
+    make
+
+    msg "test: MBEDTLS_MEMORY_BUFFER_ALLOC_C"
+    make test
+
+    msg "test: ssl-opt.sh, MBEDTLS_MEMORY_BUFFER_ALLOC_C"
+    if_build_succeeded tests/ssl-opt.sh
+}
+
 component_test_no_max_fragment_length () {
     # Run max fragment length tests with MFL disabled
     msg "build: default config except MFL extension (ASan build)" # ~ 30s