configure: Add -Wno-maybe-uninitialized to CFLAGS

The warnings generated by -Wmaybe-uninitialized are mostly spurious.
build: Do not let the install-cli target depend on a phony target

Real dependencies are preferable to phony ones where possible.
This also allows simplifying a recipe line with an automatic variable.
build: Coalesce some install recipe lines
build: Simplify phony target declaration with wildcards
build: Remove pointless empty variable settings
build: Add separate targets to (un)install import lib and shared object

This allows eliminating some conditionals within the (un)install recipes.
build: Install libdir in recipes that directly require it
build: Coalesce etags/TAGS rules
build: Set all ASFLAGS from within configure

This is how all other toolchain flags are handled.
build: Use 'DEPCC' for generating .depend, not 'CC'
cosmetic: Make .depend generation foreach loop more readable
build: Switch 'rm' to '$(RM)'
build: Split up 'install-lib-dev' into smaller subrecipes

'install-lib-headers' and 'install-lib-pc' now exist to handle
these particular tasks, allowing the use of automatic variables.
build: Use 'install-static' as a subrecipe for 'install-lib-static'

'lib-static' is now used only as the shortcut for default
build: Split install-implib

install-implib and install-implib-soname handle installation to
different directories, so that automatic variables can be used.
build: Use automatic variables with 'install-soname'
Add autotools-style silent build rules
build: Silence 'ln' when using silent rules
build: Use '$(INSTALL_DIR)' as alias for '$(INSTALL) -d'

Suppresses the echoing of directory-related INSTALL messages when
using silent rules