Fix cover bug on last expressions with empty clauses

OTP-8188 introduced a fix for handling last expressions in
expressions like case, try and friends. However the fix did
not account that some of those expressions like receive may
have no clauses (only an after clause), leading to a function
clause error when cover compiling code with such expressions.
Add spec for gen_server:terminate/6,7

This is to prevent dialyzer warning "no local return".
Add infometion about function()
erts: Fix port data memory allocation bug

for non-immediate port data >= sizeof(Eterm)*2 words.
Improve documentation about atomic operations
Merge branch 'rickard/libatomic_ops_improvements/OTP-12302' into maint

* rickard/libatomic_ops_improvements/OTP-12302:
  Improve documentation about atomic operations
asn1: Fix EXTERNAL (1994 variant) type conversion

Missed to add seqtag handling for EXTERNAL type conversion,
bug introduced in c266196c016fc1156c7a18cfeec4920ee4075519
Merge branch 'sverk/port_get_data-race/OTP-12208' into maint

* sverk/port_get_data-race/OTP-12208:
  erts: Fix port data memory allocation bug
Merge branch 'mururu/typespec-doc-about-function/OTP-12327' into maint

* mururu/typespec-doc-about-function/OTP-12327:
  Add infometion about function()
Merge branch 'josevalim/jv-cover-last-expr-maint/OTP-12328' into maint

* josevalim/jv-cover-last-expr-maint/OTP-12328:
  Fix cover bug on last expressions with empty clauses
Merge branch 'dgud/asn1/fix-seqtag/OTP-12326' into maint

* dgud/asn1/fix-seqtag/OTP-12326:
  asn1: Fix EXTERNAL (1994 variant) type conversion
Merge branch 'siri/gen_server/try-catch/OTP-12263' into maint

* siri/gen_server/try-catch/OTP-12263:
  Add spec for gen_server:terminate/6,7