Move expansion of strings in binaries to v3_core

This speeds up the compilation of binary literals
with string values in them. For example, compiling
a file with a ~340kB binary would yield the following
times by the compiler:

    Compiling "foo"
     parse_module       :   0.130 s    5327.6 kB
     transform_module   :   0.000 s    5327.6 kB
     lint_module        :   0.011 s    5327.8 kB
     expand_module      :   0.508 s   71881.2 kB
     v3_core            :   0.463 s      11.5 kB

Notice the increase in memory and processing time
in expand_module and v3_core. This happened because
expand_module would expand the string in binaries
into chars. For example, the binary <<"foo">>, which
is represented as

    {bin, 1, [
      {bin_element, 1, {string, 1, "foo"}, default, default}
    ]}

would be converted to

    {bin, 1, [
      {bin_element, 1, {char, 1, $f}, default, default},
      {bin_element, 1, {char, 1, $o}, default, default},
      {bin_element, 1, {char, 1, $o}, default, default}
    ]}

However, v3_core would then traverse all of those
characters and convert it into an actual binary, as it
is a literal value.

This patch addresses this issue by moving the expansion
of string into chars to v3_core and only if a literal
value cannot not be built. This reduces the compilation
time of the file mentioned above to the values below:

    Compiling "bar"
     parse_module       :   0.134 s    5327.6 kB
     transform_module   :   0.000 s    5327.6 kB
     lint_module        :   0.005 s    5327.8 kB
     expand_module      :   0.000 s    5328.7 kB
     v3_core            :   0.013 s      11.2 kB

1 files changed, 1 insertions, 0 deletions

diff --git a/lib/debugger/test/bs_bincomp_SUITE.erl b/lib/debugger/test/bs_bincomp_SUITE.erl
index 39e2240f2d..064e9567b3 100644
--- a/lib/debugger/test/bs_bincomp_SUITE.erl
+++ b/lib/debugger/test/bs_bincomp_SUITE.erl
@@ -66,6 +66,7 @@ end_per_group(_GroupName, Config) ->
 
 byte_aligned(Config) when is_list(Config) ->
     <<"abcdefg">> = << <<(X+32)>> || <<X>> <= <<"ABCDEFG">> >>,
+    <<"AxyzBxyzCxyz">> = << <<X, "xyz">> || <<X>> <= <<"ABC">> >>,
     <<1:32/little,2:32/little,3:32/little,4:32/little>> =
 	<< <<X:32/little>> || <<X:32>> <= <<1:32,2:32,3:32,4:32>> >>,
     <<1:32/little,2:32/little,3:32/little,4:32/little>> =