* expression.cc (class Segment_start_expression): New class definition.
(Segment_start_expression::value): New method definition.
(script_exp_function_segment_start): Return a new
Segment_start_expression.
* gold/script-c.h (script_saw_segment_start_expression): New function
prototype.
* script-sections.cc (Script_sections::Script_sections): Initialize
SAW_SEGMENT_START_EXPRESSION_ to false.
(Script_sections::set_section_addresses): Use -Ttext, -Tdata
and -Tbbs options to specify section addresses if given in
command line and no SEGMENT_START expression is seen in a script.
* script-sections.h (Script_sections::saw_segment_start_expression,
Script_sections::set_saw_segment_start_expression): New method
definition.
(Script_sections::saw_segment_start_expression_): New data member
declaration.
* script.cc (script_saw_segment_start_expression): New function.
* yyscript.y (SEGMENT_START): Call script_saw_segment_start_expression.
* testsuite/Makefile.am (check_SCRIPTS): Add script_test_6.sh,
script_test_7.sh and script_test_8.sh.
(check_DATA): Add script_test_6.stdout, script_test_7.stdout and
script_test_8.stdout.
(MOSTLYCLEANFILES): Add script_test_6, script_test_7 and script_test_8.
(script_test_6, script_test_6.stdout, script_test_7,
script_test_7.stdout, script_test_8, script_test_8.stdout): New rules.
* Makefile.in: Regenerate.
* testsuite/script_test_6.sh: New file.
* testsuite/script_test_6.t: Same.
* testsuite/script_test_7.sh: Same.
* testsuite/script_test_7.t: Same.
* testsuite/script_test_8.sh: Same.
