Fix #424 add -u/--from-url option for install.sh

The following appear to work and a build is progressing on macOS now:

./install.sh \
--from-url https://github.com/sourceryinstitute/gcc/archive/teams.tar.gz \
--package gcc \
--install-version teams \
--install-prefix=/opt/gnu/teams

where the "version" above assumes that the expanded tar ball has the
format <package-name>-<version-string>.  For example, with above,
the package tar ball should expand to a directory named gcc-teams.

Author: Damian Rouson

install.sh

@@ -164,6 +164,7 @@ info  "-n (--no-color):         ${arg_n}"
 info  "-o (--only-download):    ${arg_o}"
 info  "-p (--package):          ${arg_p}"
 info  "-P (--print-path):       ${arg_P}"
+info  "-u (--from-url):         ${arg_u}"
 info  "-U (--print-url):        ${arg_U}"
 info  "-v (--version):          ${arg_v}"
 info  "-V (--print-version):    ${arg_V}"

install.sh-usage

@@ -17,6 +17,7 @@
   -o --only-download          Download (without building) the source for the package specified by -p or --package.
   -p --package [arg]          Install specified package. Default="opencoarrays"
   -P --print-path [arg]       Print installation directory for specified package.
+  -u --from-url [arg]         Specify a URL to use for downloading a package.
   -U --print-url [arg]        Print download location for specified package.
   -v --version                Print OpenCoarrays version number.
   -V --print-version [arg]    Print version number for specified package.

prerequisites/build-functions/set_or_print_url.sh

@@ -10,6 +10,12 @@ set_or_print_url()
   # Get package name from argument passed with  -p, -D, -P, -V, or -U
   package_to_build="${arg_p:-${arg_D:-${arg_P:-${arg_U:-${arg_V:-${arg_B}}}}}}"
 
+if [[ ! -z ${arg_u:-}  ]]; then
+  # User specified a URL from which to download the package
+  url_tail=${arg_u##*/} # set url_tail to text_after_final_slash
+  url_head=${arg_u%%${url_tail}} # set url_head text before url_tail
+else
+
   if [[ "${package_to_build}" == 'cmake' ]]; then
     major_minor="${version_to_build%.*}"
   elif [[ "${package_to_build}" == "gcc" ]]; then
@@ -35,7 +41,7 @@ set_or_print_url()
      KEY="${package%%;*}"
      VALUE="${package##*;}"
      info "KEY=${KEY}  VALUE=${VALUE}"
-     
+
      if [[ "${package_to_build}" == "${KEY}" ]]; then
        # We recognize the package name so we set the URL head:
        url_head="${VALUE}"
@@ -81,6 +87,8 @@ set_or_print_url()
     emergency "Package ${package_name:-} not recognized.  Use --l or --list-packages to list the allowable names."
   fi
 
+fi # end if [[ ! -z $arg_u  ]]; then
+
   package_url="${url_head}""${url_tail}"
 
   # If a printout of the package URL was requested, then print it and exit with normal status

prerequisites/build.sh

@@ -107,6 +107,7 @@ info "-n (--no-color):         ${arg_n} "
 info "-p (--package):          ${arg_p}"
 info "-P (--print-path):       ${arg_P} "
 info "-t (--with-tau):         ${arg_t} "
+info "-u (--from-url):         ${arg_u} "
 info "-U (--print-url):        ${arg_U} "
 info "-v (--version):          ${arg_v} "
 info "-V (--print-version):    ${arg_V} "

prerequisites/build.sh-usage

@@ -19,6 +19,7 @@
   -P --print-path [arg]       Print installation path for package specified in argument.
   -t --with-tau [arg]         Use the specified TAU parallel performance utilities installation. Default="tauf90"
   -T --install-tau [arg]      Install TAU in specified path. Default="${OPENCOARRAYS_SRC_DIR}/prerequisites/installations/${package_name:-}/${version_to_build:-}/"
+  -u --from-url [arg]         Specify a URL from which to download a package. 
   -U --print-url [arg]        Print URL for package specified in argument. 
   -v --version                Print OpenCoarrays version number.
   -V --print-version [arg]    Print installation version for package specified in argument.