Error compiling Lilypond 2.19.81

[Peter Engelbert]

Hello illustrious Lilypond Developers,

I am attempting to compile Lilypond from source.  I am most definitely in
over my head--but I did manage to install all of the dependencies, such
that running configure did not reveal any errors.

I am compiling on Linux (specifically Raspbian, which is Debian Stretch on
ARM Architecture for Raspberry Pi).  The reason I'm compiling from source
is that there's no build available for ARM architecture from the lilypond
website.  When compiling (by running sudo make install), I receive the
following error.  I have no idea what it means, so I can't do anything to
fix it.  I am hoping that someone here can shed some light on what it means
so that I can get lilypond running on my Raspberry Pi!  Here is the error
message:

rm -f ./out/parser.dep; DEPENDENCIES_OUTPUT="./out/parser.dep
./out/parser.o" g++ -c -Woverloaded-virtual  -I/usr/include/python2.7
-I/usr/include/arm-linux-gnueabihf/python2.7  -fno-strict-aliasing -g
-fdebug-prefix-map=/build/python2.7-kKRR4y/python2.7-2.7.13=.
-fstack-protector-strong  -g -fwrapv  -DHAVE_CONFIG_H
-I/home/pi/repos/lilypond/lily/include -I./out
-I/home/pi/repos/lilypond/flower/include -I../flower/./out
-I../flower/include -I/home/pi/repos/lilypond/lily/out  -O2
-finline-functions -g -pipe  -I/usr/include/freetype2
-I/usr/include/pango-1.0 -I/usr/include/harfbuzz -I/usr/include/pango-1.0
-I/usr/include/glib-2.0 -I/usr/lib/arm-linux-gnueabihf/glib-2.0/include
-I/usr/include/freetype2  -W -Wall -Wconversion -o out/parser.o
out/parser.cc
./out/parser.cc: In function 'int yyparse(Lily_parser*,
scm_unused_struct**)':
./out/parser.cc:2927:12: warning: conversion to 'yytype_int16 {aka short
int}' from 'int' may alter its value [-Wconversion]
   *yyssp = yystate;
            ^~~~~~~
make[1]: *** No rule to make target '../flower/./out/library.a', needed by
'out/lilypond'.  Stop.
make[1]: Leaving directory '/home/pi/repos/lilypond/build/lily'
/home/pi/repos/lilypond/stepmake/stepmake/toplevel-targets.make:30: recipe
for target 'install' failed
make: *** [install] Error 2

Thanks, and Godspeed.
Peter